ORAU Team 

Dose Reconstruction Project for NIOSH 

External Coworker Dosimetry Data for the Hanford Site 

Document Number: 

ORAUT-OTIB-0030 

Effective Date: 11/07/2006 

Revision No.: 00 PC-1 

Controlled Copy No.: ______ 

Page 1 of 10 

Subject Expert: Steven E. Merwin 

Document Owner 

Approval: Signature on File Date: 03/10/2005 

Edward F. Maher, Task 5 Manager 

Concurrence: Signature on File Date: 03/11/2005 

Richard E. Toohey, Project Director 

Approval: Signature on File Date: 03/23/2005 

James W. Neton, Associate Director for Science 

Supersedes: 

None 

TABLE OF CONTENTS 

SECTION TITLE PAGE 

Record of Issue/Revisions ......................................................................................................................2
 

1.0	 PURPOSE ..................................................................................................................................3
 

2.0	 BACKGROUND ..........................................................................................................................3
 

3.0	 GENERAL APPROACH..............................................................................................................4
 

4.0	 APPLICATIONS AND LIMITATIONS..........................................................................................4
 

5.0	 REFERENCES ...........................................................................................................................5
 

6.0	 HANFORD COWORKER DATA DEVELOPMENT .....................................................................5
 

7.0	 HANFORD COWORKER ANNUAL DOSE SUMMARIES ..........................................................7
 

8.0	 PENTRATING DOSE VALUES BASED ON ORAUT-OTIB-0052 GUIDANCE FOR 

 SELECTED CONSTRUCTION TRADE WORKERS ..................................................................8 

LIST OF TABLES 

TABLE TITLE PAGE 

1	 Missed external doses based on Hanford Occupational External Dosimetry TBD2

 and ORAUTOTIB-0017 ..................................................................................................................................6 

2 Annual Hanford external coworker doses modified to account for missed dose ........................9 

3 Annual Hanford external penetrating coworker doses modified in accordance with ORAUTOTIB-0052 ................................................................................................................................10
 
 

Effective Date: 11/07/2006 Revision No.: 00 PC-1 Document No. ORAUT-OTIB-0030 Page 2 of 10 

RECORD OF ISSUE/REVISIONS 

ISSUE 

AUTHORIZATION 

DATE 

EFFECTIVE 

DATE REV. NO. DESCRIPTION 

03/23/2005 03/23/2005 00 New technical information bulletin to provide 

information to allow ORAU Team dose 

reconstructors to assign doses to certain 

workers at the Hanford site who have no or 

limited monitoring data, based on site 

coworker data. First approved issue. Initiated 

by Steven E. Merwin. 

03/23/2005 11/07/2006 00 PC-1 Approved page change revision due to 

release of ORAUT-OTIB-0052 Rev 00. 

Updates required language on page 3 in 

Section 1.0. Lists ORAUT-OTIB-0052 Rev 00 

as a reference on page 5 in Section 5.0. 

Rewrites item 5 on page 7 in Section 7. 

Completes Section 8.0 on page 8. Adds 

Table 3 to page 10 in Section 8.0. 

Incorporates formal internal review comments. 

Per new document requirements, added a 

Table of Contents. This revision results in an 

increase in assigned dose and a PER is 

required. Training required: As determined by 

the Task Manager. Initiated by Matthew H. 

Smith. Approval: 

Signature on File_____________10/18/2006 

John M. Byrne, Document Owner 

Signature on File_____________10/17/2006 

Edward F. Maher, Task 5 Manager 

Signature on File_____ _10/25/2006 

Kate Kimpan, Project Director 

Signature on File_____________11/07/2006 

James W. Neton, Associate Director for Science 
 

Effective Date: 11/07/2006 Revision No.: 00 PC-1 Document No. ORAUT-OTIB-0030 Page 3 of 10 

1.0 PURPOSE 

Technical information bulletins (TIBs) are not official determinations made by the National Institute for 

Occupational Safety and Health (NIOSH) but are rather general working documents that provide 

historical background information and guidance to assist in the preparation of dose reconstructions at 

particular sites or categories of sites. They will be revised in the event additional relevant information 

is obtained. TIBs may be used to assist NIOSH staff in the completion of individual dose 

reconstructions. 

In this document the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act of 2000 (42 U.S.C. § 7384l(5) and (12)). 

The purpose of this TIB is to provide information to allow ORAU Team dose reconstructors to assign 

doses to workers at the Hanford Site who have no or limited monitoring data, based on site coworker 

data. The data in this TIB are to be used in conjunction with ORAUT-OTIB-0020, “Use of Coworker 

Dosimetry Data for External Dose Assignment.”1 

2.0 BACKGROUND 

The ORAU Team is conducting a series of coworker data studies to permit dose reconstructors to 

complete certain cases for which external and/or internal monitoring data are unavailable or 

incomplete. Cases not having complete monitoring data may fall into one of several categories, 

including: 

•	 The worker was unmonitored and, even by today’s standards, did not need to be monitored 

(e.g., a non-radiological worker). 

•	 The worker was unmonitored, but by today’s standards would have been monitored. 

•	 The worker may have been monitored but the data are not available to the dose reconstructor. 

•	 The worker may have partial information, but the available information is insufficient to permit 

a dose reconstruction to occur. 

As described in ORAUT-OTIB-0020, some cases not having complete monitoring data can be 

processed based on assumptions and methodologies that do not involve coworker data. For 

example, many cases falling in the first category above can be processed by assigning ambient 

external and internal doses based on information in the relevant site Technical Basis Documents 

(TBDs). 

As described in the Hanford External Dosimetry TBD,2

 Hanford began operations in 1944 using inhouse dosimeter and processing technical support. Routine Hanford practices appear to have 

required assigning dosimeters to all workers who entered a controlled radiation area. The trends in 

the number of workers who were monitored, the number of monitored workers with positive recorded 

dose, and the collective dose do not show any abrupt changes that may be indicative of significant 

changes in photon dosimetry or assignment of dosimeters.2 Additionally, there does not appear to be 

any significant administrative practice that would jeopardize the integrity of the recorded dose of 

record. 
 

Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 4 of 10 

3.0 GENERAL APPROACH 

As described in ORAUT-OTIB-00201

, the general approach to developing coworker data for cases 

without external monitoring data involves two phases. The first phase (Phase I) permits cases to be 

processed when a “best and final” estimate of dose is not required for claim determination. The 

second phase (Phase II) facilitates the assignment of “best and final estimates” of dose, when 

necessary. This initial revision of this TIB provides coworker external dosimetry summary statistics 

applicable to Phase I dose reconstructions; coworker dose distributions applicable to Phase II dose 

reconstructions will be made available in a subsequent revision. 

4.0 APPLICATIONS AND LIMITATIONS 

1. Revision 0 of this document provides Hanford site coworker data and information that may be 

used only for clearly non-compensable cases for which a higher external dose can be assigned 

than was likely to have been actually received. Revision 1 of this document will provide dose 

distributions and additional information based on the data presented herein to permit the 

processing of clearly compensable cases or cases requiring a best estimate analysis. 

2. Some Hanford Site workers may have worked at one or more other major sites within the DOE 

complex during their employment history. Thus, the data presented herein must be used with 

caution to ensure that for clearly non-compensable, unmonitored external doses from multiple site 

employment have been overestimated. This will typically require the availability of External 

Coworker Dosimetry Data TIBs for all relevant sites. 

3. Summary statistics based on Hanford dosimetry data presented in this TIB do not extend beyond 

1989 because at the time this TIB was drafted, data beyond 1989 were not available from the 

Comprehensive Epidemiologic Data Resource (CEDR). However, the absence of these data (and 

the subsequent development of dose distributions) should not interfere with the processing of 

most Hanford cases having a lack of external dosimetry data since well before 1989 the 

monitoring and reporting practices at the site ensured that essentially all workers with a potential 

for external radiation exposure were monitored and the results are readily accessible. Should the 

need arise and sufficient data become available, coworker dosimetry data beyond the year 1989 

will be presented in a subsequent revision to this TIB. 

4. The data presented in this TIB address penetrating radiation from gamma radiation and nonpenetrating radiation from beta radiation (or low-energy photons for work involving Pu). Neutron 

data are not presented. However, the locations within the Hanford site at which neutron 

exposures were possible are limited to certain site areas and facilities, and the site TBD 

establishes a method for assigning neutron doses when relevant.2 Therefore, the TBD should be 

used as the basis for assigning neutron doses, when relevant, in addition to the photon and/or 

beta doses assigned in accordance with this TIB. 

5. For the years 1972 and later, external on-site ambient doses should not be included in addition to 

the co-worker doses assigned in accordance with this TIB, because any such doses would have 

been included in the dosimetry results reported by the site which were used as the basis for the 

coworker dose distributions presented below.2 Prior to 1972, co-worker doses assigned in 

accordance with this TIB must be supplemented by the appropriate external on-site ambient dose 

in accordance with the instructions in ORAUT-PROC-0060.4 
 

Effective Date: 11/07/2006 Revision No.: 00 PC-1 Document No. ORAUT-OTIB-0030 Page 5 of 10 

5.0 REFERENCES 

1. ORAU Team, ORAUT-OTIB-0020, Use of Coworker Dosimetry Data for External Dose 

Assignment, Rev. 00, December 29, 2004 

2. ORAU Team, ORAUT-TKBS-0006-6, Technical Basis Document for the Hanford Site – 

Occupational External Dose, Rev. 01, January 9, 2004. 

3. NIOSH (National Institute for Occupational Safety and Health), External Dose Reconstruction 

Implementation Guideline, Rev. 0, OCAS-IG-001, Office of Compensation Analysis and Support, 

Cincinnati, Ohio, 2002. 

4. ORAU Team, ORAUT-PROC-0060, External On-Site Ambient Dose Reconstruction for DOE 

Sites, Rev. 00, January 31, 2005. 

5. ORAU Team, ORAUT-OTIB-0017, Interpretation of Dosimetry Data for Assignment of Shallow 

Dose, Rev 00., January 11, 2005. 

6. ORAU Team, ORAUT-OTIB-0052, Parameters to Consider When Processing Claims for 

Construction Trade Workers, Rev. 00, August 31, 2006. 

6.0 HANFORD COWORKER DATA DEVELOPMENT 

Dosimetry data for monitored Hanford workers from the CEDR databases maintained by the U.S. 

Department of Energy (DOE) were selected for this evaluation. The CEDR data evaluated 

represented primarily annual penetrating and non-penetrating dosimetry data provided by the Hanford 

site, which pertain to the shielded and “open-window minus shielded” dosimetry readings, 

respectively, and exclude neutron doses. Starting in 1982, multiple badge readings are recorded in 

CEDR for some Hanford workers; however, this was a relatively small fraction of the total, and the 

adjustments made for partial years of employment (see Section 7) are likely to account for any data 

that do not encompass a full year. Also, starting in 1983 the CEDR data included the reported 

shallow dose, not the non-penetrating dose. Thus, for these years, the non-penetrating doses were 

derived by subtracting the reported penetrating doses from the reported shallow doses. 

Between 1957 and 1971, the Hanford Site film dosimeter included a third measurement (in addition to 

the standard shielded and open-window measurement) using a special filter covering a portion of the 

film designed to allow the assessment of X-ray doses. Thus, doses in this time period were reported 

as beta, gamma, and X-ray. A fraction (0.65) of the X-ray dose was assumed to contribute to nonpenetrating dose, and the remainder (0.35) was assumed to contribute to penetrating dose. Since the 

CEDR data include the X-ray doses reported by the site for this period, the coworker dose evaluations 

described in this TIB include an upward adjustment of the reported beta and gamma doses during this 

period by adding 65% and 35% of the reported X-ray doses, respectively, to arrive at the reported 

non-penetrating and penetrating doses. 

The validity of the CEDR data was confirmed by selecting a sampling of claimant dosimetry data 

submitted by the site as part of the EEOICPA Subtitle B program and comparing it to the pertinent 

CEDR data. A review of annual data for ten claimants covering 297 worker-years of employment at 

Hanford indicated excellent agreement between the two data sets. Specifically, the reported 

penetrating and non-penetrating data in the CEDR database were found to correspond to the reported 

external and “skin minus external” annual doses reported in the site Radiological Exposure System. It 

is concluded that the CEDR data are acceptable for the development of coworker doses for the 
Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 6 of 10 

Hanford Site, with adjustments made for the reported X-ray doses as appropriate, as described 

above. 

Adjustment for Missed Dose 

According to the External Dose Reconstruction Implementation Guideline,3

 missed doses are to be 

assigned for null dosimeter readings to account for the possibility that doses were received but not 

recorded by the dosimeter or reported by the site. Annual missed doses are calculated by multiplying 

the number of null badge readings by the dosimeter limit of detection (LOD) and summing the results. 

These values are used as the 95th percentile of a lognormal distribution for the purpose of calculating 

probability of causation; thus, in IREP the calculated missed doses are multiplied by 0.5 and entered 

in Parameter 1, and a value of 1.52 is entered in Parameter 2, to represent the geometric mean and 

geometric standard deviation, respectively. 

The assignment of missed doses for monitored workers is particularly significant for Hanford 

claimants prior to 1951 when workers were monitored weekly, and between 1951 and 1957 when 

workers were monitored biweekly. Table 1 lists the maximum annual missed dose by era and type of 

radiation (penetrating gamma and non-penetrating) based on information presented in the site TBD2 

and ORAUT-OTIB-0017.5 

Table 1. Missed external doses based on Hanford Occupational External Dosimetry TBD2 and 

ORAUT-OTIB-0017.5 

Period 

Penetrating 

LOD (rem) 

Non-penetrating 

LOD (rem)a 

Exchange 

frequency 

Maximum annual missed dose (rem) 

Penetrating Non-penetrating 

1944a

-1950 0.04 0.05 Weekly 2.080 2.600 

1951-1956 0.04 0.05 Biweekly 1.040 1.300 

1957 0.04 0.05 Variedb

 0.720 0.900 

1958-1971 0.04 0.05 Monthly 0.480 0.600 

1972-1994 0.02 0.03 Monthlyc

 0.240 0.360 

1994-present 0.01 0.05 Monthlyc

 0.120 0.600 

a. Hanford instituted a weekly exchange and the use of film dosimeters in October 1944. 

b. The exchange frequency was biweekly through May 1957, then monthly. A total of 18 exchanges were assumed for the 

year. 

c. The TBD indicates that either monthly or quarterly exchange frequencies were used. Monthly exchanges have been 

assumed here to ensure favorability to the claimant. 

Special Considerations 

Certain aspects of the external dosimetry practices at the Hanford Site documented in the TBD2

 were 

considered in the analysis of the site data. These include: 

•	 In some cases, values less than the dosimeter LOD were reported by the site. For example, 

values as low as 10 or 20 mR were reported even though the penetrating LOD was considered 

to be 40 mrem (or 40 mR) prior to 1972. 

•	 The data available to analyze coworker doses represent annual dose summaries for individual 

workers. Because these data include partial work years, the average annual doses reported 

tend to underestimate the average annual doses received by employees who worked an entire 

year. 

As described in Section 7.0 below, a favorable to claimant approach was adopted in the development 

of coworker dose summaries, and this approach should account for any underestimate of doses to 

radiological workers at the Hanford site based on the considerations described above. 
 

7.0 

Effective Date: 11/07/2006 Revision No.: 00 PC-1 Document No. ORAUT-OTIB-0030 Page 7 of 10 

HANFORD COWORKER ANNUAL DOSE SUMMARIES 

Based on the information and approaches described above, Hanford coworker annual external 

dosimetry summaries were developed for use in the evaluation of external dose for certain claimants 

potentially exposed to workplace radiation, but with no or limited monitoring data provided by DOE. 

These summaries were developed using the following steps: 

1. As described in Section 6.0 above, the penetrating and non-penetrating doses available from 

CEDR, which represented annual summary data, were modified to account for partial years of 

employment. This adjustment was made by analyzing the NOCTS employment data for Hanford 

workers and adjusting the reported doses upward by an appropriate multiplier corresponding to 

the average fraction of a year an employee worked at the site. For example, if in a particular 

calendar year the average employment period for all Hanford employees in NOCTS was 11 

months, the CEDR annual doses were multiplied by 12/11, or 1.09. This permits the dose 

reconstructor to assign an appropriate prorated dose to account for partial years of employment or 

potential exposure. A factor of 4 was applied for the year 1944 when monitoring at the site did not 

begin until October. 

2. For the years 1957 through 1971, when X-ray doses were reported separately in addition to the 

reported gamma and beta doses, but were not included in the reported annual penetrating and 

non-penetrating doses, the penetrating and non-penetrating doses were modified by adding 35% 

and 65% of the reported positive X-ray doses, respectively.2,5 

3. The 50th, 95th and 99th percentile annual penetrating and non-penetrating doses were derived for 

two scenarios: excluding and including reported zeroes. 

4. The 50th, 95th and 99th percentile doses based on the exclusion of zeroes were used as the 

basis for the coworker data set, since these are representative of radiological worker doses which 

are the principal focus of the coworker studies. However, to ensure favorability to the claimant, for 

penetrating radiation the percentile doses with zero results included were evaluated, and if the 

addition of one-half of the maximum annual non-penetrating missed doses (listed in Table 1) to 

these percentile doses resulted in values exceeding the percentile doses based on the exclusion 

of zeroes, the latter were replaced with the former. Missed doses were not added to both the 

penetrating and non-penetrating results because the non-penetrating results reported by the site 

reflect the difference between the open-window and shielded measurements, and assigning 

missed dose to both measurements would result in a double counting since a positive shielded 

measurement exceeding the non-penetrating MDL would appear as a positive open-window 

measurement. To ensure favorability to the claimant, the non-penetrating MDLs were assigned in 

the calculations (since they exceed the penetrating MDLs), and the values were apportioned to the 

penetrating doses (since penetrating doses are assigned as gamma radiation, which in IREP 

cannot have a negative effect because the radiation effectiveness factors for gammas are equal to 

or greater than for >15 keV electrons). 

5. The results are presented in Table 2 below. These percentile doses should be used for selected 

Hanford workers with no or limited monitoring data using the methodologies outlined in Section 7.0 

of ORAUT-OTIB-0020.1 

Doses to organs impacted only by penetrating radiation (e.g., organs other than the skin, breast and 

testes) are calculated based only on the “Gamma” columns in Table 2 combined with the appropriate 

organ dose conversion factors (DCFs).3

 Doses to the skin, breast and testes (and any other cancer 

location potentially impacted by non-penetrating radiation) are determined based on both the 
8.0 

Effective Date: 11/07/2006 Revision No.: 00 PC-1 Document No. ORAUT-OTIB-0030 Page 8 of 10 

“Gamma” and “Non-penetrating” columns; gamma doses are assigned as photons with an energy 

range consistent with information in the external dosimetry TBD for the Hanford site,2

 and nonpenetrating doses are assigned as electrons >15 keV with corrections applied to account for clothing 

attenuation or other applicable considerations, or photons <30 keV, depending on the employment 

location and job description. 

PENTRATING DOSE VALUES BASED ON ORAUT-OTIB-0052 GUIDANCE FOR 

SELECTED CONSTRUCTION TRADE WORKERS 

Table 3 contains penetrating dose values that have been adjusted using the guidance given in 

Section 8.0 of ORAUT-OTIB-0052, “Parameters to Consider When Processing Claims for 

Construction Trade Workers.”6

 This guidance is applicable for construction trade workers who meet 

the criteria given in Section 3.0 of ORAUT-OTIB-0052.6 
 

Effective Date: 03/23/2005 Revision No.: 00 Document No. ORAUT-OTIB-0030 Page 9 of 10 

Table 2. Annual Hanford external coworker doses modified to 

account for missed dose (rem). 

Year 

Gamma 

99th% 

Gamma 

95th% 

Gamma 

50th% 

Non-pen 

99th% 

Non-pen 

95th% 

Non-pen 

50th% 

1944 3.096 2.176 1.300 3.363 1.448 0.240 

1945 3.294 2.430 1.336 4.215 0.631 0.071 

1946 2.917 2.125 1.448 5.944 1.421 0.297 

1947 2.113 1.708 1.369 3.130 1.081 0.222 

1948 1.805 1.541 1.334 5.400 1.096 0.149 

1949 1.818 1.572 1.357 3.895 1.076 0.215 

1950 2.107 1.721 1.357 3.222 1.535 0.239 

1951 2.263 1.278 0.685 4.276 2.047 0.212 

1952 2.504 1.541 0.721 2.782 1.046 0.155 

1953 2.691 1.815 0.779 2.828 1.477 0.188 

1954 3.053 1.863 0.720 2.438 1.260 0.175 

1955 3.246 2.059 0.717 2.230 1.287 0.200 

1956 3.344 2.306 0.682 2.262 1.189 0.141 

1957 3.325 2.318 0.650 1.755 0.942 0.119 

1958 3.236 2.599 0.321 1.326 0.695 0.074 

1959 2.867 2.237 0.300 2.120 1.122 0.127 

1960 3.276 2.756 0.311 2.622 1.419 0.162 

1961 3.293 2.877 0.364 1.938 1.001 0.075 

1962 3.406 3.018 0.452 1.695 0.805 0.108 

1963 3.389 2.981 0.406 1.715 0.760 0.050 

1964 3.437 3.018 0.505 1.954 0.690 0.042 

1965 4.849 3.880 0.881 2.338 0.905 0.098 

1966 3.574 2.690 0.524 1.881 0.841 0.056 

1967 4.118 3.179 0.385 3.161 1.476 0.073 

1968 3.473 2.801 0.436 2.253 0.890 0.084 

1969 3.529 2.905 0.354 2.147 0.923 0.075 

1970 3.689 3.159 0.323 2.623 1.267 0.092 

1971 3.776 2.726 0.394 2.978 1.237 0.165 

1972 3.458 2.339 0.293 1.060 0.565 0.090 

1973 3.380 2.142 0.246 1.729 0.535 0.055 

1974 3.473 2.099 0.283 1.253 0.513 0.068 

1975 3.337 1.933 0.283 1.201 0.549 0.080 

1976 3.091 1.667 0.226 0.741 0.359 0.069 

1977 3.748 2.188 0.206 1.026 0.365 0.052 

1978 2.934 1.252 0.214 0.530 0.237 0.034 

1979 2.967 1.257 0.202 0.662 0.276 0.044 

1980 2.658 0.968 0.203 0.551 0.293 0.045 

1981 2.596 1.103 0.191 0.620 0.425 0.092 

1982 2.980 1.432 0.191 0.533 0.329 0.057 

1983 3.081 1.933 0.180 0.603 0.261 0.045 

1984 2.785 1.643 0.191 0.723 0.321 0.034 

1985 2.911 1.849 0.180 0.834 0.297 0.034 

1986 2.851 1.985 0.180 0.714 0.312 0.022 

1987 2.260 1.048 0.195 0.403 0.135 0.015 

1988 0.360 0.236 0.180 0.101 0.045 0.011 

1989 0.508 0.236 0.180 0.124 0.034 0.011 
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Table 3. Annual Hanford external 

penetrating coworker doses modified in 

accordance with ORAUT-OTIB-0052 

(rem). 

Year 

Gamma 

99th% 

Gamma 

95th% 

Gamma 

50th% 

1944 3.814 2.526 1.300 

1945 4.092 2.882 1.350 

1946 3.564 2.455 1.508 

1947 2.439 1.871 1.397 

1948 2.007 1.637 1.348 

1949 2.025 1.681 1.379 

1950 2.430 1.889 1.380 

1951 2.909 1.529 0.699 

1952 3.246 1.898 0.750 

1953 3.507 2.281 0.831 

1954 4.014 2.348 0.748 

1955 4.284 2.622 0.743 

1956 4.421 3.076 0.695 

1957 4.395 3.245 0.650 

1958 4.411 3.639 0.329 

1959 3.900 3.132 0.310 

1960 4.466 3.859 0.315 

1961 4.490 3.907 0.389 

1962 4.649 4.106 0.512 

1963 4.625 4.054 0.449 

1964 4.692 4.106 0.588 

1965 6.669 5.312 1.114 

1966 4.883 3.645 0.614 

1967 5.645 4.381 0.420 

1968 4.742 3.801 0.491 

1969 4.820 4.068 0.375 

1970 5.081 4.422 0.332 

1971 5.166 3.817 0.432 

1972 4.770 3.269 0.338 

1973 4.661 2.964 0.273 

1974 4.790 2.939 0.324 

1975 4.600 2.706 0.324 

1976 4.327 2.334 0.245 

1977 5.177 3.063 0.216 

1978 4.108 1.753 0.227 

1979 4.154 1.760 0.211 

1980 3.649 1.355 0.212 

1981 3.634 1.544 0.196 

1982 4.172 2.005 0.196 

1983 4.313 2.706 0.180 

1984 3.899 2.300 0.196 

1985 4.075 2.589 0.180 

1986 3.991 2.780 0.180 

1987 3.165 1.467 0.201 

1988 0.456 0.259 0.180 

1989 0.712 0.283 0.180