customers comes either through procurement processes conducted by the IPA or through markets operated by MISO.
The IPA administers an RFP process through which Ameren Illinois procures its expected supply obligation.
The power and related procurement costs incurred by Ameren Illinois are passed directly to its customers through a cost recovery mechanism.
Ameren Illinois charges transmission and distribution service rates to customers who purchase electricity from alternative retail electric suppliers.
See Note 14 – Related Party Transactions and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report for additional information on power procurement in Illinois.
POWER GENERATION The following table presents the source of Ameren’s and Ameren Missouri’s electric generation, excluding purchased power, for the years ended December 31, 2015, 2014, and 2013:
## Table 0 ##
(a) Renewable power generation includes production from Ameren Missouri’s hydroelectric, methane gas, and solar energy centers, but it excludes purchased renewable energy credits.
(b) Less than 1% of total fuel supply.
The following table presents the cost of fuels for electric generation for the years ended December 31, 2015, 2014, and 2013:
## Table 1 ##
(a) The cost of coal and the costs for transportation, which include hedges for railroad diesel fuel surcharges.
(b) The cost of uranium and its processing to become nuclear fuel.
(c) The cost of natural gas and fixed and variable costs for transportation, storage, balancing, and fuel losses for delivery to the energy center.
(d) All costs, including transportation, for fuels used in our energy centers, including coal, nuclear, natural gas, methane gas, and oil.
Methane gas and oil are not individually listed in this table because their use is minimal.
Coal Ameren Missouri has an ongoing need for coal for generation, so it pursues a price-hedging strategy consistent with this requirement.
Ameren Missouri has agreements in place to purchase coal and to transport it to energy centers.
Most of Ameren Missouri’s coal supply agreements expire at the end of 2017, and its existing coal transport agreements expire at the end of 2019.
Ameren Missouri has additional coal supply contracts in place to provide a portion of its coal supply in 2018.
Ameren Missouri has coal transport agreements with Union Pacific Railroad and Burlington Northern Santa Fe Railway.
As of December 31, 2015, Ameren Missouri had price-hedged 100% of its expected coal supply and coal transportation requirements for generation in 2016.
Ameren Missouri burned 18 million tons of coal in 2015.
About 98% of Ameren Missouri’s coal is purchased from the Powder River Basin in Wyoming.
The remaining coal is typically purchased from the Illinois Basin.
Inventory may be adjusted because of generation levels or uncertainties of supply due to potential work stoppages, delays in coal deliveries, equipment breakdowns, and other factors.
Deliveries from the Powder River Basin have occasionally been restricted because of rail congestion and maintenance, derailments, and weather.
As of December 31, 2015, coal inventories for Ameren Missouri were near targeted levels.
Disruptions in coal deliveries could cause Ameren Missouri to pursue a strategy that could include reducing sales of power during low-margin periods, buying higher-cost fuels to generate required electricity, and purchasing power from other sources.
Nuclear The production of nuclear fuel involves the mining and milling of uranium ore to produce uranium concentrates, the conversion of uranium concentrates to uranium hexafluoride gas, the enrichment of that gas, the conversion of the enriched uranium hexafluoride gas into uranium dioxide fuel pellets, and the fabrication into usable fuel assemblies.
Ameren Missouri has entered into uranium, uranium conversion, uranium enrichment, and fabrication contracts to procure the fuel supply for its Callaway nuclear energy center.
The Callaway energy center requires refueling at 18-month intervals.
The last refueling was completed in November 2014.
The next refuelings are scheduled for the spring of 2016 and the fall of 2017.
As of December 31,
At December 31, 2009, Aon had domestic federal operating loss carryforwards of $7 million that will expire at various dates from 2010 to 2024, state operating loss carryforwards of $513 million that will expire at various dates from 2010 to 2028, and foreign operating and capital loss carryforwards of $453 million and $252 million, respectively, nearly all of which are subject to indefinite carryforward.
Unrecognized Tax Benefits The following is a reconciliation of the Company’s beginning and ending amount of unrecognized tax benefits (in millions):
## Table 2 ##
As of December 31, 2009, $61 million of unrecognized tax benefits would impact the effective tax rate if recognized.
Aon does not expect the unrecognized tax positions to change significantly over the next twelve months.
The Company recognizes penalties and interest related to unrecognized income tax benefits in its provision for income taxes.
Aon accrued potential penalties of less than $1 million during each of 2009, 2008 and 2007.
Aon accrued interest of $2 million during 2009 and less than $1 million during both 2008 and 2007.
As of December 31, 2009 and 2008, Aon has recorded a liability for penalties of $5 million and $4 million, respectively, and for interest of $18 million and $14 million, respectively.
Aon and its subsidiaries file income tax returns in the U. S.  federal jurisdiction as well as various state and international jurisdictions.
Aon has substantially concluded all U. S.  federal income tax matters for years through 2006.
Material U. S.  state and local income tax jurisdiction examinations have been concluded for years through 2002.
Aon has concluded income tax examinations in its primary international jurisdictions through 2002.
Notes to the Financial Statements — Continued The tax effect of temporary differences, which gave rise to deferred tax assets and liabilities, is as follows
## Table 3 ##
In April 2007, the New York State statutory income tax rate decreased from 7.5% to 7.1%, retroactive to January 1, 2007.
The rate decrease resulted in a reduction of $20 million and $19 million to the net accumulated deferred tax liabilities for Con Edison and Con Edison of New York, respectively, of which $19 million and $18 million were deferred for customers’ benefit for Con Edison and Con Edison of New York, respectively Reconciliation of the difference between income tax expense and the amount computed by applying the prevailing statutory income tax rate to income before income taxes is as follows
## Table 4 ##
Uncertain Tax Positions In January 2007, the Companies adopted FIN 48.
This interpretation clarifies the accounting for uncertain tax positions in accordance with FASB Statement No.109.
Under the interpretation, an enterprise is not allowed to recognize, in its financial statements, the benefit of a tax position unless that position is more likely than not to be sustained upon examinatio by taxing authorities, including resolution of any related appeals and litigation processes, based solely on the technical merits of the position.
The IRS has essentially completed its field audits of the Companies’ federal income tax returns through 2007.
The Companies’ federal income tax returns for 2002 through 2007
Valuation Techniques.
The U. S.  core fixed income fund is valued at NAV.
The fund strategy seeks total return consisting of income and capital appreciation primarily by investing in a broad range of investment-grade debt securities, including U. S.  government obligations, corporate bonds, mortgage-backed securities, asset-backed securities and money market instruments.
There are no restrictions on redemptions (which are usually within one business day of notice).
Money market funds are classified within Level 1 of the fair value hierarchy because they are valued using quoted market prices in active markets.
Equity securities are valued at the closing price reported on the active market on which the individual securities are traded and, as such, are classified within Level 1 of the fair value hierarchy.
Fixed income securities (government securities, corporate bonds, asset-backed securities, collateralized mortgagebacked securities and municipal bonds) are valued using a bid-evaluation price or a mid-evaluation price.
These evaluations are based on quoted prices, if available, or models that use observable inputs and, as such, are classified within Level 2 of the fair value hierarchy.
FCX’s embedded derivatives on provisional copper concentrate, copper cathode and gold purchases and sales are valued using only quoted monthly LME or COMEX copper forward prices and the adjusted LBMA gold prices at each reporting date based on the month of maturity (refer to Note 14 for further discussion); however, FCX’s contracts themselves are not traded on an exchange.
FCX’s embedded derivatives on provisional cobalt purchases are valued using quoted monthly LME cobalt forward prices or average published Metals Bulletin cobalt prices, subject to certain adjustments as specified by the terms of the contracts, at each reporting date based on the month of maturity.
As a result, these derivatives are classified within Level 2 of the fair value hierarchy.
FCX’s derivative financial instruments for copper futures and swap contracts and copper forward contracts that are traded on the respective exchanges are classified within Level 1 of the fair value hierarchy because they are valued using quoted monthly COMEX or LME prices at each reporting date based on the month of maturity (refer to Note 14 for further discussion).
Certain of these contracts are traded on the over-the-counter market and are classified within Level 2 of the fair value hierarchy based on COMEX and LME forward prices.
The fair value of contingent consideration for the sales of TFHL and onshore California oil and gas properties (refer to Note 2 for further discussion) is calculated based on average commodity price forecasts through applicable maturity dates using a Monte-Carlo simulation model.
The models use various observable inputs, including Brent crude oil forward prices, historical copper and cobalt prices, volatilities, discount rates and settlement terms.
As a result, these contingent consideration assets are classified within Level 2 of the fair value hierarchy.
The fair value of contingent consideration for the sale of Deepwater GOM oil and gas properties (refer to Note 2 for further discussion) is calculated based on a discounted cash flow model using inputs that include third-party estimates for reserves, production rates and production timing, and discount rates.
Because significant inputs are not observable in the market, the contingent consideration is classified within Level 3 of the fair value hierarchy.
Long-term debt, including current portion, is valued using available market quotes and, as such, is classified within Level 2 of the fair value hierarchy.
The techniques described above may produce a fair value calculation that may not be indicative of NRV or reflective of future fair values.
Furthermore, while FCX believes its valuation techniques are appropriate and consistent with those used by other market participants, the use of different techniques or assumptions to determine fair value of certain financial instruments could result in a different fair value measurement at the reporting date.
There have been no changes in the techniques used at December 31, 2018.
A summary of the changes in the fair value of FCX’s Level 3 instrument, contingent consideration for the sale of the Deepwater GOM oil and gas properties, for the years ended December 31 follows:

<table><tr><td></td><td>Coal</td><td>Nuclear</td><td>Natural Gas/Oil</td><td>Renewables<sup>(a)</sup></td></tr><tr><td>2015</td><td>71%</td><td>25%(b)</td><td></td><td>4%</td></tr><tr><td>2014</td><td>76</td><td>21(b)</td><td></td><td>3</td></tr><tr><td>2013</td><td>77</td><td>20(b)</td><td></td><td>3</td></tr></table>
<table><tr><td>Cost of Fuels(dollars per mmbtu)</td><td>2015</td><td>2014</td><td>2013</td></tr><tr><td>Coal<sup>(a)</sup></td><td>$2.193</td><td>$2.151</td><td>$2.050</td></tr><tr><td>Nuclear<sup>(b)</sup></td><td>0.928</td><td>0.918</td><td>0.942</td></tr><tr><td>Natural gas<sup>(c)</sup></td><td>7.422</td><td>11.226</td><td>7.907</td></tr><tr><td>Weighted average – all fuels<sup>(d)</sup></td><td>$1.910</td><td>$1.936</td><td>$1.874</td></tr></table>
<table><tr><td></td><td>2009</td><td>2008</td></tr><tr><td>Balance at January 1</td><td>$86</td><td>$70</td></tr><tr><td>Additions based on tax positions related to the current year</td><td>2</td><td>5</td></tr><tr><td>Additions for tax positions of prior years</td><td>5</td><td>12</td></tr><tr><td>Reductions for tax positions of prior years</td><td>-11</td><td>-11</td></tr><tr><td>Settlements</td><td>-10</td><td>-4</td></tr><tr><td>Lapse of statute of limitations</td><td>-3</td><td>-1</td></tr><tr><td>Acquisitions</td><td>6</td><td>21</td></tr><tr><td>Foreign currency translation</td><td>2</td><td>-6</td></tr><tr><td>Balance at December 31</td><td>$77</td><td>$86</td></tr></table>
<table><tr><td></td><td colspan="2"> Con Edison</td><td colspan="2"> Con Edison of New York</td></tr><tr><td> (Millions of Dollars)</td><td> 2008</td><td> 2007</td><td> 2008</td><td> 2007</td></tr><tr><td>Deferred tax liabilities:</td><td></td><td></td><td></td><td></td></tr><tr><td>Depreciation</td><td>$2,363</td><td>$2,075</td><td>$2,230</td><td>$1,873</td></tr><tr><td>Regulatory liability – future income tax</td><td>1,374</td><td>1,240</td><td>1,296</td><td>1,165</td></tr><tr><td>Unrecognized pension and other postretirement costs – SFAS No. 158</td><td>2,284</td><td>855</td><td>2,172</td><td>794</td></tr><tr><td>State income tax</td><td>557</td><td>474</td><td>482</td><td>394</td></tr><tr><td>Capitalized overheads</td><td>479</td><td>432</td><td>437</td><td>399</td></tr><tr><td>Other</td><td>539</td><td>544</td><td>330</td><td>378</td></tr><tr><td>Total deferred tax liabilities</td><td>7,596</td><td>5,620</td><td>6,947</td><td>5,003</td></tr><tr><td>Deferred tax assets:</td><td></td><td></td><td></td><td></td></tr><tr><td>Unrecognized pension and other postretirement costs – SFAS No. 158</td><td>2,284</td><td>855</td><td>2,172</td><td>794</td></tr><tr><td>Regulatory asset – future income tax</td><td>185</td><td>125</td><td>168</td><td>109</td></tr><tr><td>State income tax</td><td>49</td><td>47</td><td>16</td><td>18</td></tr><tr><td>Other</td><td>151</td><td>207</td><td>49</td><td>139</td></tr><tr><td>Total deferred tax assets</td><td>2,669</td><td>1,234</td><td>2,405</td><td>1,060</td></tr><tr><td> Net Liabilities</td><td>4,927</td><td>4,386</td><td>4,542</td><td>3,943</td></tr><tr><td> Investment Tax Credits</td><td>72</td><td>79</td><td>69</td><td>75</td></tr><tr><td> Deferred Income Taxes and Investment Tax Credits</td><td>$4,999</td><td>$4,465</td><td>$4,611</td><td>$4,018</td></tr><tr><td> Deferred Income Taxes – Recoverable Energy Costs</td><td>70</td><td>86</td><td>59</td><td>77</td></tr><tr><td> Total Deferred Income Taxes and Investment Tax Credits</td><td>$5,069</td><td>$4,551</td><td>$4,670</td><td>$4,095</td></tr></table>
<table><tr><td></td><td colspan="3">Con Edison</td><td colspan="3">Con Edison of New York</td></tr><tr><td> (% of Pre-tax income)</td><td>2008</td><td>2007</td><td>2006</td><td>2008</td><td>2007</td><td>2006</td></tr><tr><td> Statutory Tax Rate</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Federal</td><td>35%</td><td>35%</td><td>35%</td><td>35%</td><td>35%</td><td>35%</td></tr><tr><td>Changes in computed taxes resulting from:</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>State income tax</td><td>6</td><td>5</td><td>5</td><td>5</td><td>4</td><td>5</td></tr><tr><td>Depreciation related differences</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td></tr><tr><td>Cost of removal</td><td>-5</td><td>-6</td><td>-6</td><td>-6</td><td>-6</td><td>-6</td></tr><tr><td>Other</td><td>-1</td><td>-3</td><td>-1</td><td>-2</td><td>-3</td><td>-2</td></tr><tr><td>Effective Tax Rate</td><td>36%</td><td>32%</td><td>34%</td><td>33%</td><td>31%</td><td>33%</td></tr></table>

Question: considering the years 2008 and 2009 , what is the increase observed in the liability for interest?
Answer: 0.28571