A reconciliation of the beginning and ending amount of gross unrecognized tax benefits for uncertain tax positions, including positions impacting only the timing of tax benefits, follows.
## Table 0 ##
We classify interest and penalties on income taxes as a component of the provision for income taxes.
We recognized a net provision for interest and penalties of $38 million, $34 million and $20 million during the years ended December 31, 2017, 2016 and 2015, respectively.
The total amount of interest and penalties accrued was $157 million and $120 million as of December?31, 2017 and 2016, respectively.
On January 31, 2018, we received a Revenue Agent’s Report from the IRS indicating the end of the field examination of our U. S.  income tax returns for 2010 to 2012.
In the audits of 2007 to 2012 including the impact of a loss carryback to 2005, the IRS has proposed to tax in the United States profits earned from certain parts transactions by CSARL, based on the IRS examination team’s application of the “substance-over-form” or “assignment-of-income” judicial doctrines.
We are vigorously contesting the proposed increases to tax and penalties for these years of approximately $2.3 billion.
We believe that the relevant transactions complied with applicable tax laws and did not violate judicial doctrines.
We have filed U. S.  income tax returns on this same basis for years after 2012.
Based on the information currently available, we do not anticipate a significant increase or decrease to our unrecognized tax benefits for this matter within the next 12 months.
We currently believe the ultimate disposition of this matter will not have a material adverse effect on our consolidated financial position, liquidity or results of operations.
With the exception of a loss carryback to 2005, tax years prior to 2007 are generally no longer subject to U. S.  tax assessment.
In our major non-U.
S.  jurisdictions including Australia, Brazil, China, Germany, Japan, Mexico, Switzerland, Singapore and the U. K. , tax years are typically subject to examination for three to ten years.
Due to the uncertainty related to the timing and potential outcome of audits, we cannot estimate the range of reasonably possible change in unrecognized tax benefits in the next 12 months.
Finite-lived intangible assets are amortized over their estimated useful lives and tested for impairment if events or changes in circumstances indicate that the asset may be impaired.
In 2016, gross customer relationship intangibles of $96 million and related accumulated amortization of $27 million as well as gross intellectual property intangibles of $111 million and related accumulated amortization of $48 million from the Resource Industries segment were impaired.
The fair value of these intangibles was determined to be insignificant based on an income approach using expected cash flows.
The fair value determination is categorized as Level 3 in the fair value hierarchy due to its use of internal projections and unobservable measurement inputs.
The total impairment of $132 million was a result of restructuring activities and is included in Other operating (income) expense in Statement 1.
See Note 25 for information on restructuring costs.
Amortization expense related to intangible assets was $323 million, $326 million and $337 million for 2017, 2016 and 2015, respectively.
As of December 31, 2017, amortization expense related to intangible assets is expected to be:
## Table 1 ##
B.
Goodwill There were no goodwill impairments during 2017 or 2015.
Our annual impairment tests completed in the fourth quarter of 2016 indicated the fair value of each reporting unit was substantially above its respective carrying value, including goodwill, with the exception of our Surface Mining & Technology reporting unit.
The Surface Mining & Technology reporting unit, which primarily serves the mining industry, is a part of our Resource Industries segment.
The goodwill assigned to this reporting unit is largely from our acquisition of Bucyrus International, Inc.  in 2011.
Its product portfolio includes large mining trucks, electric rope shovels, draglines, hydraulic shovels and related parts.
In addition to equipment, Surface Mining & Technology also develops and sells technology products and services to provide customer fleet management, equipment management analytics and autonomous machine capabilities.
The annual impairment test completed in the fourth quarter of 2016 indicated that the fair value of Surface Mining & Technology was below its carrying value requiring the second step of the goodwill impairment test process.
The fair value of Surface Mining & Technology was determined primarily using an income approach based on a discounted ten year cash flow.
We assigned the fair value to Surface Mining & Technology’s assets and liabilities using various valuation techniques that required assumptions about royalty rates, dealer attrition, technological obsolescence and discount rates.
The resulting implied fair value of goodwill was below the carrying value.
Accordingly, we recognized a goodwill impairment charge of $595 million, which resulted in goodwill of $629 million remaining for Surface Mining & Technology as of October 1, 2016.
The fair value determination is categorized as Level 3 in the fair value hierarchy due to its use of internal projections and unobservable measurement inputs.
There was a $17 million tax benefit associated with this impairment charge.
ÿþThe assumed discount rate is used to discount future benefit   obligations back to today s dollars.
 The U.
S.
 discount rate is based   on a benefit cash flow-matching approach and represents the rate   at which our benefit obligations could effectively be settled as of   our measurement date, December 31.
 The benefit cash flowmatching approach involves analyzing Caterpillar s projected cash   flows against a high quality bond yield curve, calculated using a wide   population of corporate Aa bonds available on the measurement   date.
 The very highest and lowest yielding bonds (top and bottom   10 percent) are excluded from the analysis.
 A similar process is used   to determine the assumed discount rate for our most significant   non-U.
S.
 plans.
 This rate is sensitive to changes in interest rates.
   A decrease in the discount rate would increase our obligation and   future expense.
  B.
 Plan assets  @T@  In general, our strategy for both the U.
S.
 and non-U.
S.
 pensions   includes ongoing alignment of our investments to our liabilities, while   reducing risk in our portfolio.
 The current U.
S.
 pension target asset   allocation is 30 percent equities and 70 percent fixed income.
 This   target allocation will be revisited periodically to ensure it reflects   our overall objectives.
 The non-U.
S.
 pension weighted-average   target allocations are 38 percent equities, 54 percent fixed income,   5 percent real estate and 3 percent other.
 The target allocations   for each plan vary based upon local statutory requirements,   demographics of plan participants and funded status.
 The non-U.
S.
   plan assets are primarily invested in non-U.
S.
 securities.
  Our target allocation for the other postretirement benefit plans is 70   percent equities and 30 percent fixed income.
   The U.
S.
 plans are rebalanced to plus or minus 5 percentage   points of the target asset allocation ranges on a monthly basis.
 The   frequency of rebalancing for the non-U.
S.
 plans varies depending   on the plan.
 As a result of our diversification strategies, there are no   significant concentrations of risk within the portfolio of investments.
  The use of certain derivative instruments is permitted where   appropriate and necessary for achieving overall investment policy   objectives.
 The plans do not engage in derivative contracts for   speculative purposes.
  The accounting guidance on fair value measurements specifies a   fair value hierarchy based upon the observability of inputs used in   valuation techniques (Level 1, 2 and 3).
 See Note 18 for a discussion   of the fair value hierarchy.
  Fair values are determined as follows:  "  Equity securities are primarily based on valuations for identical   instruments in active markets.
  "  Fixed income securities are primarily based upon models that   take into consideration such market-based factors as recent   sales, risk-free yield curves and prices of similarly rated bonds.
  "  Real estate is stated at the fund s net asset value or at   appraised value.
  "  Cash, short-term instruments and other are based on the   carrying amount, which approximates fair value, or the fund s   net asset value.

## Table 2 ##
and $1,088 million, respectively, were primarily comprised of loans to dealers, and the SPC’s liabilities of $1,106 million and $1,087 million, respectively, were primarily comprised of commercial paper.
The assets of the SPC are not available to pay Cat Financial’s creditors.
Cat Financial may be obligated to perform under the guarantee if the SPC experiences losses.
No loss has been experienced or is anticipated under this loan purchase agreement.
Cat Financial is party to agreements in the normal course of business with selected customers and Caterpillar dealers in which they commit to provide a set dollar amount of financing on a preapproved basis.
They also provide lines of credit to certain customers and Caterpillar dealers, of which a portion remains unused as of the end of the period.
Commitments and lines of credit generally have fixed expiration dates or other termination clauses.
It has been Cat Financial’s experience that not all commitments and lines of credit will be used.
Management applies the same credit policies when making commitments and granting lines of credit as it does for any other financing.
Cat Financial does not require collateral for these commitments/ lines, but if credit is extended, collateral may be required upon funding.
The amount of the unused commitments and lines of credit for dealers as of December 31, 2017 and 2016 was $10,993 million and $12,775 million, respectively.
The amount of the unused commitments and lines of credit for customers as of December 31, 2017 and 2016 was $3,092 million and $3,340 million, respectively.
Our product warranty liability is determined by applying historical claim rate experience to the current field population and dealer inventory.
Generally, historical claim rates are based on actual warranty experience for each product by machine model/engine size by customer or dealer location (inside or outside North America).
Specific rates are developed for each product shipment month and are updated monthly based on actual warranty claim experience.
## Table 3 ##
22.
Environmental and legal matters The Company is regulated by federal, state and international environmental laws governing our use, transport and disposal of substances and control of emissions.
In addition to governing our manufacturing and other operations, these laws often impact the development of our products, including, but not limited to, required compliance with air emissions standards applicable to internal combustion engines.
We have made, and will continue to make, significant research and development and capital expenditures to comply with these emissions standards.
We are engaged in remedial activities at a number of locations, often with other companies, pursuant to federal and state laws.
When it is probable we will pay remedial costs at a site, and those costs can be reasonably estimated, the investigation, remediation, and operating and maintenance costs are accrued against our earnings.
Costs are accrued based on consideration of currently available data and information with respect to each individual site, including available technologies, current applicable laws and regulations, and prior remediation experience.
Where no amount within a range of estimates is more likely, we accrue the minimum.
Where multiple potentially responsible parties are involved, we consider our proportionate share of the probable costs.
In formulating the estimate of probable costs, we do not consider amounts expected to be recovered from insurance companies or others.
We reassess these accrued amounts on a quarterly basis.
The amount recorded for environmental remediation is not material and is included in Accrued expenses.
We believe there is no more than a remote chance that a material amount for remedial activities at any individual site, or at all the sites in the aggregate, will be required.
On January 7, 2015, the Company received a grand jury subpoena from the U. S.  District Court for the Central District of Illinois.
The subpoena requests documents and information from the Company relating to, among other things, financial information concerning U. S.  and non-U.
S.  Caterpillar subsidiaries (including undistributed profits of non-U.
S.  subsidiaries and the movement of cash among U. S.  and non-U.
S.  subsidiaries).
The Company has received additional subpoenas relating to this investigation requesting additional documents and information relating to, among other things, the purchase and resale of replacement parts by Caterpillar Inc.  and non-U.
S.  Caterpillar subsidiaries, dividend distributions of certain non-U.
S.  Caterpillar subsidiaries, and Caterpillar SARL and related structures.
On March 2-3, 2017, agents with the Department of Commerce, the Federal Deposit Insurance Corporation and the Internal Revenue Service executed search and seizure warrants at three facilities of the Company in the Peoria, Illinois area, including its former corporate headquarters.
The warrants identify, and agents seized, documents and information related to, among other things, the export of products from the United States, the movement of products between the United States and Switzerland, the relationship between Caterpillar Inc.  and Caterpillar SARL, and sales outside the United States.
It is the Company’s understanding that the warrants, which concern both tax and export activities, are related to the ongoing grand jury investigation.
The Company is continuing to cooperate with this investigation.
The Company is unable to predict the outcome or reasonably estimate any potential loss; however, we currently believe that this matter will not have a material adverse effect on the Company’s consolidated results of operations, financial position or liquidity.
On March 20, 2014, Brazil’s Administrative Council for Economic Defense (CADE) published a Technical Opinion which named 18 companies and over 100 individuals as defendants, including two subsidiaries of Caterpillar Inc. , MGE - Equipamentos e Servi?os Ferroviários Ltda.
(MGE) and Caterpillar Brasil Ltda.
The publication of the Technical Opinion opened CADE’s official administrative investigation into allegations that the defendants participated in anticompetitive bid activity for the construction and maintenance of metro and train networks in Brazil.
While companies cannot be
Our total credit commitments and available credit as of December?31, 2017 were:

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td>Years ended December 31,</td></tr><tr><td>(Millions of dollars)</td><td>2017</td><td>2016</td></tr><tr><td>Balance at January 1,</td><td>$1,032</td><td>$968</td></tr><tr><td>Additions for tax positions related to current year</td><td>270</td><td>73</td></tr><tr><td>Additions for tax positions related to prior years</td><td>20</td><td>55</td></tr><tr><td>Reductions for tax positions related to prior years</td><td>-27</td><td>-36</td></tr><tr><td>Reductions for settlements<sup>2</sup></td><td>-9</td><td>-24</td></tr><tr><td>Reductions for expiration of statute of limitations</td><td>—</td><td>-4</td></tr><tr><td>Balance at December 31,</td><td>$1,286</td><td>$1,032</td></tr><tr><td>Amount that, if recognized, would impact the effective tax rate</td><td>$1,209</td><td>$963</td></tr></table>
<table><tr><td>2018</td><td>2019</td><td>2020</td><td>2021</td><td>2022</td><td>Thereafter</td></tr><tr><td>$322</td><td>$316</td><td>$305</td><td>$287</td><td>$268</td><td>$613</td></tr></table>
<table><tr><td></td><td colspan="2">U.S. Pension Benefits</td><td colspan="2">Non-U.S.Pension Benefits</td><td colspan="2">Other PostretirementBenefits</td></tr><tr><td>(Millions of dollars)</td><td>2017</td><td>2016</td><td>2017</td><td>2016</td><td>2017</td><td>2016</td></tr><tr><td>Change in plan assets:</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Fair value of plan assets, beginning of year</td><td>$11,354</td><td>$11,440</td><td>$3,887</td><td>$3,890</td><td>$550</td><td>$650</td></tr><tr><td>Actual return on plan assets</td><td>1,692</td><td>860</td><td>350</td><td>503</td><td>101</td><td>55</td></tr><tr><td>Foreign currency exchange rates</td><td>—</td><td>—</td><td>278</td><td>-392</td><td>—</td><td>—</td></tr><tr><td>Company contributions</td><td>1,350</td><td>36</td><td>107</td><td>117</td><td>155</td><td>176</td></tr><tr><td>Participant contributions</td><td>—</td><td>—</td><td>6</td><td>7</td><td>59</td><td>57</td></tr><tr><td>Benefits paid</td><td>-977</td><td>-970</td><td>-203</td><td>-238</td><td>-361</td><td>-388</td></tr><tr><td>Settlements and termination benefits</td><td>-3</td><td>-12</td><td>-120</td><td>—</td><td>—</td><td>—</td></tr><tr><td>Fair value of plan assets, end of year</td><td>$13,416</td><td>$11,354</td><td>$4,305</td><td>$3,887</td><td>$504</td><td>$550</td></tr></table>
<table><tr><td>(Millions of dollars)</td><td>2017</td><td>2016</td></tr><tr><td>Warranty liability, January 1</td><td>$1,258</td><td>$1,354</td></tr><tr><td>Reduction in liability (payments)</td><td>-860</td><td>-909</td></tr><tr><td>Increase in liability (new warranties)</td><td>1,021</td><td>813</td></tr><tr><td>Warranty liability, December 31</td><td>$1,419</td><td>$1,258</td></tr></table>

Question: In the year/section with the most Fair value of plan assets, beginning of year, what is the growth rate of Actual return on plan assets?
Answer: 0.51128
Reasoning program: add(1692,350), add(#0,101), add(860,503), add(#2,55), subtract(#1,#3), add(860,503), add(#5,55), divide(#4,#6)