The following table summarizes the calculation of FFO for the years ended December 31, 2008, 2007 and 2006, respectively (in thousands):
## Table 0 ##
During 2008, we continued to execute within our core areas of competency, while making adjustments due to the general disruption in the U. S.  economy.
Highlights of our operating activities are as follows: ?
In December 2008, we sold 16 acres of land in Alexandria, VA, to the United States government for the development of an administrative office complex for the U. S.  Department of the Army.
The land sale, for $105.1 million, is part of an overall $953.1 million development and construction agreement with the U. S.  Army Corps of Engineers that implements the 2005 Base Realignment and Closure Commission (the “BRAC Construction Contract”) and will continue through 2011.
The development will consist of facilities containing more than 1.7 million square feet, and includes two multistory office towers, two parking garages and a public transportation center.
The total anticipated profit on the overall agreement will be recognized over the course of the contract using the percentage of completion method of accounting.  ?
During 2008, we sold seven newly developed properties to unconsolidated joint ventures from which we received $251.6 million of sales and financing proceeds and recognized pre-tax gains on sale of $23.3 million.
We also sold seven Build-for-Sale properties to third parties for $120.5 million of gross proceeds and recognized pre-tax gains on sale of $18.8 million.  ?
We disposed of eight wholly owned heldfor-rental properties for $79.4 million of gross proceeds and also generated $47.4 million of gross proceeds, excluding the government contract described above, from the divestiture of non-strategic land parcels.  ?
The current state of the economy has limited our ability to access debt and equity capital markets.
Management’s priorities with regard to uses of capital for development of new properties, therefore, have been re-evaluated and new wholly owned development commitments have been significantly curtailed.
As such, the total cost of our wholly owned properties under construction totaled $372.6 million at December 31, 2008 with $142.5 million of such costs having been incurred through that date.
Our total cost for joint venture properties under construction was $356.6 million at December 31, 2008 with $189.6 million of costs incurred through that date.  ?
The occupancy level for our in-service heldfor-rental portfolio (including joint venture properties) decreased from 92.1% at December 31, 2007 to 89.5% at December 31, 2008.
The decrease was primarily the result of developments which were not fully leased being placed in service during 2008.
However, occupancy of this portfolio did improve over the last two quarters of the year as we experienced positive net leasing absorption for the year.
The decrease in occupancy at December 31, 2008, as compared to December 31, 2007, is primarily the result of developments which were not fully leased being placed in service during 2008.
Certain of these developments were built with the intention to sell shortly after completion but, due to economic conditions, were not sold and are being held as rental properties for the foreseeable future.
Our ongoing ability to maintain favorable occupancy levels may be adversely affected by the impact of workforce reductions triggered by the current economic downturn on current and prospective tenants and such a reduction in the level of occupancy may have an adverse impact on revenues from rental operations.
There are no significant differences in occupancy between wholly owned properties and properties held by unconsolidated subsidiaries.
Lease Expiration and Renewals: Our ability to maintain and improve occupancy rates primarily depends upon our continuing ability to re-lease expiring space.
The following table reflects our in-service portfolio lease expiration schedule by property type as of December 31, 2008.
The table indicates square footage and annualized net effective rents (based on December 2008 rental revenue) under expiring leases (in thousands, except percentage data):
## Table 1 ##
Note: Includes all properties in unconsolidated joint ventures and excludes all Build-for-Sale properties.
We renewed 71.9% and 79.7% of our leases up for renewal totaling approximately 9.2 million and 9.8 million square feet in 2008 and 2007, respectively.
We attained 1.80% growth in net effective rents on these renewals during 2008.
Excluding the effect of one significant 322,679 square foot early lease renewal in certain of our office properties, our growth in net effective rents for 2008 would have been 4.90%, which is more consistent with our 2007 growth in net effective rent rate upon renewal of 5.81%.
Our lease renewal percentages over the past three years have remained relatively consistent at a 70-80% success rate.
The effects of current economic conditions upon our base of existing tenants may adversely affect our ability to continue to achieve this renewal rate.
Future Development: Another source of our earnings growth is our wholly owned and joint venture development activities.
We expect to generate future earnings through income upon the sale of these development properties or from Rental Operations income as the development properties are placed in service and leased.
Considering the current state of the economy and the risks presented by constraints on our ability to access capital on favorable
estimated with reasonable accuracy.
The percentage of completion estimates are based on a comparison of the contract expenditures incurred to the estimated final costs.
Changes in job performance, job conditions and estimated profitability may result in revisions to costs and income and are recognized in the period in which the revisions are determined.
Unbilled receivables on construction contracts totaled $22.7 million and $33.1 million at December 31, 2008 and 2007, respectively.
Property Sales Gains on sales of all properties are recognized in accordance with SFAS 66.
The specific timing of the sale is measured against various criteria in SFAS 66 related to the terms of the transactions and any continuing involvement in the form of management or financial assistance from the seller associated with the properties.
We make judgments based on the specific terms of each transaction as to the amount of the total profit from the transaction that we recognize considering factors such as continuing ownership interest we may have with the buyer (“partial sales”) and our level of future involvement with the property or the buyer that acquires the assets.
If the sales criteria are not met, we defer gain recognition and account for the continued operations of the property by applying the finance, installment or cost recovery methods, as appropriate, until the full accrual sales criteria are met.
Estimated future costs to be incurred after completion of each sale are included in the determination of the gain on sales.
Gains from sales of depreciated property are included in discontinued operations and the proceeds from the sale of these held-for-rental properties are classified in the investing activities section of the Consolidated Statements of Cash Flows.
Gains or losses from our sale of properties that were developed or repositioned with the intent to sell and not for long-term rental (“Build-forSale” properties) are classified as gain on sale of Build-for-Sale properties in the Consolidated Statements of Operations.
All activities and proceeds received from the development and sale of these buildings are classified in the operating activities section of the Consolidated Statements of Cash Flows.
Net Income Per Common Share Basic net income per common share is computed by dividing net income available for common shareholders by the weighted average number of common shares outstanding for the period.
Diluted net income per common share is computed by dividing the sum of net income available for common shareholders and the minority interest in earnings allocable to Units not owned by us, by the sum of the weighted average number of common shares outstanding and minority Units outstanding, including any potential dilutive securities for the period.
The following table reconciles the components of basic and diluted net income per common share (in thousands):
## Table 2 ##
(1) Excludes (in thousands of shares) 7,731, 780 and 719 of anti-dilutive shares for the years ended December 31, 2008, 2007 and 2006, respectively.
Also excludes the 3.75% Exchangeable Senior Notes due November 2011 (“Exchangeable Notes”) issued in 2006, that have an anti-dilutive effect on earnings per share for the years ended December 31, 2008, 2007 and 2006.
A joint venture partner in one of our unconsolidated companies has the option to convert a portion of its ownership in the joint venture to our common shares.
The effect of this option on earnings per share was anti-dilutive for the years ended December 31, 2008, 2007 and 2006.
We utilized multiple broker estimates in estimating the fair value.
Our unsecured notes are thinly traded and, in many cases, the broker estimates were not based upon comparable transactions.
As such, we have determined that our estimation of the fair value of our fixed rate unsecured debt was primarily based upon Level 3 inputs.
The indentures (and related supplemental indentures) governing our outstanding series of notes also require us to comply with financial ratios and other covenants regarding our operations.
We were in compliance with all such covenants as of December 31, 2008.
Unsecured Lines of Credit Our unsecured lines of credit as of December 31, 2008 are described as follows (in thousands):
## Table 3 ##
We use the DRLP unsecured line of credit to fund development activities, acquire additional rental properties and provide working capital.
This line of credit provides us with an option to obtain borrowings from financial institutions that participate in the line, at rates that may be lower than the stated interest rate, subject to certain restrictions.
The stated rate on the amounts outstanding on the DRLP unsecured line of credit as of December 31, 2008 was LIBOR plus .525% (ranging from 1.005% to 2.355% as of December 31, 2008).
We may, solely at our option, exercise an option to extend the maturity date to January 2011.
This line of credit also contains various financial covenants that require us to meet financial ratios and defined levels of performance, including those related to fixed charge, variable rate indebtedness, consolidated net worth and debt-to-net asset value.
As of December 31, 2008, we were in compliance with all covenants under this line of credit.
The consolidated subsidiary’s unsecured line of credit allows for borrowings up to $30.0 million at a rate of LIBOR plus .85% (equal to 1.32% for outstanding borrowings as of December 31, 2008).
This unsecured line of credit is used to fund development activities within the consolidated subsidiary and matures in July 2011 with a 12-month extension option.
The fair value of our unsecured lines of credit as of December 31, 2008 was $477.1 million.
We utilized a discounted cash flow methodology in order to estimate the fair value.
The net present value of the difference between future contractual interest payments and future interest payments based on our estimate of a current market rate represents the difference between the book value and the fair value.
Our estimate of a current market rate is based upon the rate, considering current market conditions and our specific credit profile, at which we estimate we could obtain similar borrowings.
The current market rate we utilized was internally estimated; therefore, we have concluded that our determination of fair value for our unsecured lines of credit was primarily based upon Level 3 inputs.
Scheduled Maturities and Interest Paid At December 31, 2008, the scheduled amortization and maturities of all indebtedness for the next five years and thereafter were as follows (in thousands):

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td></td><td>2008</td><td>2007</td><td>2006</td></tr><tr><td></td><td>Net income available for common shareholders</td><td>$56,616</td><td>$217,692</td><td>$145,095</td></tr><tr><td>Adjustments:</td><td></td><td></td><td></td><td></td></tr><tr><td>Depreciation and amortization</td><td></td><td>314,952</td><td>277,691</td><td>254,268</td></tr><tr><td>Company share of joint venture depreciation and amortization</td><td></td><td>38,321</td><td>26,948</td><td>18,394</td></tr><tr><td>Earnings from depreciable property sales – wholly owned</td><td></td><td>-16,961</td><td>-121,072</td><td>-42,089</td></tr><tr><td>Earnings from depreciable property sales – share of joint venture</td><td></td><td>-495</td><td>-6,244</td><td>-18,802</td></tr><tr><td>Minority interest share of adjustments</td><td></td><td>-16,527</td><td>-10,983</td><td>-18,858</td></tr><tr><td>Funds From Operations</td><td></td><td>$375,906</td><td>$384,032</td><td>$338,008</td></tr></table>
<table><tr><td></td><td colspan="3">Total Portfolio</td><td colspan="2">Industrial</td><td colspan="2">Office</td><td colspan="2">Other</td></tr><tr><td>Year of Expiration</td><td>Square Feet</td><td>Ann. RentRevenue</td><td>% of Revenue</td><td>Square Feet</td><td>Ann. RentRevenue</td><td>Square Feet</td><td>Ann. RentRevenue</td><td>Square Feet</td><td>Ann. RentRevenue</td></tr><tr><td>2009</td><td>11,842</td><td>$75,705</td><td>10%</td><td>8,702</td><td>$34,063</td><td>3,076</td><td>$40,975</td><td>64</td><td>$667</td></tr><tr><td>2010</td><td>14,066</td><td>95,747</td><td>12%</td><td>10,222</td><td>43,795</td><td>3,831</td><td>51,765</td><td>13</td><td>187</td></tr><tr><td>2011</td><td>16,219</td><td>95,831</td><td>12%</td><td>12,593</td><td>47,246</td><td>3,556</td><td>47,410</td><td>70</td><td>1,175</td></tr><tr><td>2012</td><td>12,062</td><td>82,274</td><td>11%</td><td>8,511</td><td>33,122</td><td>3,503</td><td>48,278</td><td>48</td><td>874</td></tr><tr><td>2013</td><td>12,748</td><td>103,662</td><td>13%</td><td>7,803</td><td>32,167</td><td>4,887</td><td>70,601</td><td>58</td><td>894</td></tr><tr><td>2014</td><td>10,619</td><td>65,503</td><td>8%</td><td>8,179</td><td>29,888</td><td>2,404</td><td>34,993</td><td>36</td><td>622</td></tr><tr><td>2015</td><td>8,746</td><td>66,137</td><td>9%</td><td>6,318</td><td>25,237</td><td>2,427</td><td>40,871</td><td>1</td><td>29</td></tr><tr><td>2016</td><td>5,058</td><td>33,825</td><td>4%</td><td>3,585</td><td>12,285</td><td>1,262</td><td>19,097</td><td>211</td><td>2,443</td></tr><tr><td>2017</td><td>6,424</td><td>44,010</td><td>6%</td><td>4,599</td><td>18,145</td><td>1,562</td><td>22,492</td><td>263</td><td>3,373</td></tr><tr><td>2018</td><td>6,850</td><td>48,979</td><td>6%</td><td>5,123</td><td>22,542</td><td>1,222</td><td>18,815</td><td>505</td><td>7,622</td></tr><tr><td>2019 and Thereafter</td><td>9,110</td><td>66,216</td><td>9%</td><td>6,811</td><td>30,251</td><td>2,021</td><td>29,849</td><td>278</td><td>6,116</td></tr><tr><td></td><td>113,744</td><td>$777,889</td><td>100%</td><td>82,446</td><td>$328,741</td><td>29,751</td><td>$425,146</td><td>1,547</td><td>$24,002</td></tr><tr><td>Total Portfolio Square Feet</td><td>127,130</td><td></td><td></td><td>91,596</td><td></td><td>33,843</td><td></td><td>1,691</td><td></td></tr><tr><td>Percent Occupied</td><td>89.5%</td><td></td><td></td><td>90.0%</td><td></td><td>87.9%</td><td></td><td>91.5%</td><td></td></tr></table>
<table><tr><td></td><td>2008</td><td>2007</td><td>2006</td></tr><tr><td>Basic net income available for common shareholders</td><td>$56,616</td><td>$217,692</td><td>$145,095</td></tr><tr><td>Minority interest in earnings of common unitholders</td><td>2,968</td><td>14,399</td><td>14,238</td></tr><tr><td>Diluted net income available for common shareholders</td><td>$59,584</td><td>$232,091</td><td>$159,333</td></tr><tr><td>Weighted average number of common shares outstanding</td><td>146,915</td><td>139,255</td><td>134,883</td></tr><tr><td>Weighted average partnership Units outstanding</td><td>7,619</td><td>9,204</td><td>13,186</td></tr><tr><td>Dilutive shares for stock-based compensation plans -1</td><td>507</td><td>1,155</td><td>1,324</td></tr><tr><td>Weighted average number of common shares and potential dilutive securities</td><td>155,041</td><td>149,614</td><td>149,393</td></tr></table>
<table><tr><td>Description</td><td>BorrowingCapacity</td><td>MaturityDate</td><td>Outstandingat December 31, 2008</td></tr><tr><td>Unsecured Line of Credit – DRLP</td><td>$1,300,000</td><td>January 2010</td><td>$474,000</td></tr><tr><td>Unsecured Line of Credit – Consolidated Subsidiary</td><td>$30,000</td><td>July 2011</td><td>$9,659</td></tr></table>

Question: what was the percentage improvement in the unbilled receivables on construction contracts from 2007 to 2008
Answer: -0.3142
Reasoning program: subtract(22.7,33.1), divide(#0,33.1)