THE AES CORPORATION NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) DECEMBER 31, 2012, 2011, AND 2010 Performance Stock Units—The Company issues performance stock units (“PSUs”) to officers under its long-term compensation plan.
PSUs are restricted stock units of which 50% of the units awarded include a market condition and the remaining 50% include a performance condition.
Vesting will occur if the applicable continued employment conditions are satisfied and (a) for the units subject to the market condition the Total Stockholder Return (“TSR”) on AES common stock exceeds the TSR of the Standard and Poor’s 500 Utilities Sector Index over the three-year measurement period beginning on January 1st of the grant year and ending on December 31st of the third year and (b) for the units subject to the performance condition if the Company’s actual Adjusted EBITDA meets the performance target over the three-year measurement period beginning on January 1, 2012 and ending on December 31, 2014.
The market and performance condition determines the vesting and final share equivalent per PSU and can result in earning an award payout range of 0% to 200%, depending on the achievement.
In all circumstances, PSUs granted by AES do not entitle the holder the right, or obligate AES, to settle the restricted stock unit in cash or other assets of AES.
The effect of the market condition on PSUs issued to officers of the Company during 2012 is reflected in the award’s fair value on the grant date.
The results of the valuation estimated the fair value at $19.75 per share, equating to 144% of the Company’s closing stock price on the date of grant.
PSUs that included a market condition granted during the year ended December 31, 2012, 2011 and 2010 had a grant date fair value per RSU of $19.75, $17.68 and $11.57, respectively.
The fair value of the PSUs with a performance condition had a grant date fair value of $13.70 equal to the closing price of the Company’s stock on the grant date.
The Company believes that it is probable that the performance condition will be met; this will continue to be evaluated throughout the performance period.
If the fair value of the market condition was not applied to PSUs issued to officers, the total grant date fair value of PSUs granted during the year ended December 31, 2012 would have decreased by $2 million.
Restricted stock units with a market condition were awarded to officers of the Company prior to 2011 contained only the market condition measuring the TSR on AES common stock.
These units were required to be held for an additional two years subsequent to vesting before they could be converted into shares and become transferable.
There is no such requirement for the shares granted during 2011 and afterwards.
The following table summarizes the components of the Company’s stock-based compensation related to its PSUs recognized in the Company’s consolidated financial statements:
## Table 0 ##
(1) Amount represents fair market value on the date of conversion.
There was no cash used to settle PSUs or compensation cost capitalized as part of the cost of an asset for the years ended December 31, 2012, 2011 and 2010.
As of December 31, 2012, $6 million of total unrecognized compensation cost related to PSUs is expected to be recognized over a weighted average period of approximately 1.9 years.
There were no modifications to PSU awards during the year ended December 31, 2012.
## Table 1 ##
(1) Represents the total contract/notional amount of the derivatives outstanding and includes both short and long positions.
The table above presents the contract/notional amounts and credit risk amounts at December 31, 2007 and 2006 of all the Corporation’s derivative positions.
These derivative positions are primarily executed in the over-the-counter market.
The credit risk amounts take into consideration the effects of legally enforceable master netting agreements, and on an aggregate basis have been reduced by the cash collateral applied against derivative assets.
At December 31, 2007 and 2006, the cash collateral applied against derivative assets on the Consolidated Balance Sheet was $12.8 billion and $7.3 billion.
In addition, at December 31, 2007 and 2006, the cash collateral placed against derivative liabilities was $10.0 billion and $6.5 billion.
ALM Activities Interest rate contracts and foreign exchange contracts are utilized in the Corporation’s ALM activities.
The Corporation maintains an overall interest rate risk management strategy that incorporates the use of interest rate contracts to minimize significant fluctuations in earnings that are caused by interest rate volatility.
The Corporation’s goal is to manage interest rate sensitivity so that movements in interest rates do not significantly adversely affect net interest income.
As a result of interest rate fluctuations, hedged fixed-rate assets and liabilities appreciate or depreciate in market value.
Gains or losses on the derivative instruments that are linked to the hedged fixed-rate assets and liabilities are expected to substantially offset this unrealized appreciation or depreciation.
Interest income and interest expense on hedged variable-rate assets and liabilities increase or decrease as a result of interest rate fluctuations.
Gains and losses on the derivative instruments that are linked to these hedged assets and liabilities are expected to substantially offset this variability in earnings.
Interest rate contracts, which are generally non-leveraged generic interest rate and basis swaps, options and futures, allow the Corporation to manage its interest rate risk position.
Non-leveraged generic interest rate swaps involve the exchange of fixed-rate and variable-rate interest payments based on the contractual underlying notional amount.
Basis swaps involve the exchange of interest payments based on the contractual underlying notional amounts, where both the pay rate and the receive rate are floating rates based on different indices.
Option products primarily consist of caps, floors and swaptions.
Futures contracts used for the Corporation’s ALM activities are primarily index futures providing for cash payments based upon the movements of an underlying rate index.
The Corporation uses foreign currency contracts to manage the foreign exchange risk associated with certain foreign currency-denominated assets and liabilities, as well as the Corporation’s investments in foreign subsidiaries.
Foreign exchange contracts, which include spot and forward contracts, represent agreements to exchange the currency of one country for the currency of another country at an agreed-upon price on an agreedupon settlement date.
Exposure to loss on these contracts will increase or decrease over their respective lives as currency exchange and interest rates fluctuate.
Fair Value, Cash Flow and Net Investment Hedges The Corporation uses various types of interest rate and foreign exchange derivative contracts to protect against changes in the fair value of its assets and liabilities due to fluctuations in interest rates and exchange rates (fair value hedges).
The Corporation also uses these types of contracts to protect against changes in the cash flows of its assets and liabilities, and other forecasted transactions (cash flow hedges).
During the next 12 months, net losses on derivative instruments included in accumulated OCI of approximately $1.3 billion ($820 million net-of-tax) are expected to be reclassified into earnings.
These net losses reclassified into earnings are expected to impact net interest income related to the respective hedged items.
of 2014, which reduced income tax expense by approximately $45 million.
In 2013, the R&D tax credit was temporarily reinstated for two years, retroactive to the beginning of 2012.
As a result, income tax expense for 2013 reflects the credit for all of 2013 and 2012, which reduced income tax expense by approximately $76 million.
We receive a tax deduction for dividends paid on shares of our common stock held by certain of our defined contribution plans with an employee stock ownership plan feature.
The amount of the tax deduction has increased as we increased our dividend over the last three years, partially offset by a decline in the number of shares in these plans.
A limited amount of the 2014 and 2013 non-cash goodwill impairment charges will be deductible for tax purposes.
Accordingly, the 2014 and 2013 non-cash goodwill impairment charges (Note 1) of $119 million and $195 million, respectively, increased our 2014 and 2013 effective tax rates.
As a result of a decision in 2015 to divest Lockheed Martin Commercial Flight Training in 2016, we recorded an asset impairment charge of approximately $90 million.
This charge was partially offset by a net deferred tax benefit of about $80 million.
The net impact of the resulting tax benefit reduced the effective income tax rate by 1.0 percentage point in 2015.
We participate in the IRS Compliance Assurance Process program.
The IRS examination of the year 2012 was completed in the fourth quarter of 2013.
The examinations of the years 2013 and 2014 remain under review.
The primary components of our federal and foreign deferred income tax assets and liabilities at December 31 were as follows (in millions):
## Table 2 ##
(a) The increase in 2015 was primarily due to the negative investment return on postretirement plan assets (Note 11).
(b) A valuation allowance was provided against certain foreign company deferred tax assets arising from carryforwards of unused tax benefits.
(c) Includes deferred taxes associated with the exchange of debt securities in prior years.
(d) Includes net foreign current deferred tax liabilities, which are included on the Balance Sheets in other current liabilities.
As of December 31, 2015 and 2014, our liabilities associated with unrecognized tax benefits are not material.
We and our subsidiaries file income tax returns in the U. S.  federal jurisdiction and various foreign jurisdictions.
With few exceptions, the statute of limitations is no longer open for U. S.  federal or non-U.
S.  income tax examinations for the years before 2012, other than with respect to refunds.
U. S.  income taxes and foreign withholding taxes have not been provided on earnings of $353 million, $291 million, and $222 million that have not been distributed by our non-U.
S.  companies as of December 31, 2015, 2014, and 2013.
Our intention is to permanently reinvest these earnings, thereby indefinitely postponing their remittance to the U. S.  If these earnings had been remitted, we estimate that the additional income taxes after foreign tax credits would have been approximately $48 million in 2015, $55 million in 2014, and $50 million in 2013.
Our federal and foreign income tax payments, net of refunds received, were $1.8 billion in 2015, $1.5 billion in 2014, and $787 million in 2013.
Our 2014 net payments reflect a $200 million refund from the IRS primarily attributable to our tax-deductible discretionary pension contributions during the fourth quarters of 2013.
Performance Graph The following graph compares the total return, assuming reinvestment of dividends, on an investment in the Company, based on performance of the Company's common stock, with the total return of the Standard & Poor's 500 Composite Stock Index and the Dow Jones United States Travel and Leisure Index for a five year period by measuring the changes in common stock prices from December 31, 2012 to December 31, 2017.
## Table 3 ##
The stock performance graph assumes for comparison that the value of the Company's common stock and of each index was $100 on December 31, 2012 and that all dividends were reinvested.
Past performance is not necessarily an indicator of future results.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td colspan="3">December 31,</td></tr><tr><td></td><td>2012</td><td>2011</td><td>2010</td></tr><tr><td></td><td colspan="3">(in millions)</td></tr><tr><td>PSU expense before income tax</td><td>$5</td><td>$5</td><td>$4</td></tr><tr><td>Tax benefit</td><td>-1</td><td>-1</td><td>-1</td></tr><tr><td>PSU expense, net of tax</td><td>$4</td><td>$4</td><td>$3</td></tr><tr><td>Total value of PSUs converted<sup>-1</sup></td><td>$—</td><td>$—</td><td>$3</td></tr><tr><td>Total fair value of PSUs vested</td><td>2</td><td>—</td><td>—</td></tr></table>
<table><tr><td></td><td colspan="2"> December 31, 2007</td><td colspan="2">December 31, 2006</td></tr><tr><td>(Dollars in millions)</td><td> Contract/ Notional<sup>-1</sup></td><td> Credit Risk</td><td>Contract/ Notional<sup>-1</sup></td><td>Credit Risk</td></tr><tr><td> Interest rate contracts</td><td></td><td></td><td></td><td></td></tr><tr><td>Swaps</td><td>$22,472,949</td><td>$15,368</td><td>$18,185,655</td><td>$9,601</td></tr><tr><td>Futures and forwards</td><td>2,596,146</td><td>10</td><td>2,283,579</td><td>103</td></tr><tr><td>Written options</td><td>1,402,626</td><td>–</td><td>1,043,933</td><td>–</td></tr><tr><td>Purchased options</td><td>1,479,985</td><td>2,508</td><td>1,308,888</td><td>2,212</td></tr><tr><td> Foreign exchange contracts</td><td></td><td></td><td></td><td></td></tr><tr><td>Swaps</td><td>505,878</td><td>7,350</td><td>451,462</td><td>4,241</td></tr><tr><td>Spot, futures and forwards</td><td>1,600,683</td><td>4,124</td><td>1,234,009</td><td>2,995</td></tr><tr><td>Written options</td><td>341,148</td><td>–</td><td>464,420</td><td>–</td></tr><tr><td>Purchased options</td><td>339,101</td><td>1,033</td><td>414,004</td><td>1,391</td></tr><tr><td> Equity contracts</td><td></td><td></td><td></td><td></td></tr><tr><td>Swaps</td><td>56,300</td><td>2,026</td><td>32,247</td><td>577</td></tr><tr><td>Futures and forwards</td><td>12,174</td><td>10</td><td>19,947</td><td>24</td></tr><tr><td>Written options</td><td>166,736</td><td>–</td><td>102,902</td><td>–</td></tr><tr><td>Purchased options</td><td>195,240</td><td>6,337</td><td>104,958</td><td>7,513</td></tr><tr><td> Commodity contracts</td><td></td><td></td><td></td><td></td></tr><tr><td>Swaps</td><td>13,627</td><td>770</td><td>4,868</td><td>1,129</td></tr><tr><td>Futures and forwards</td><td>14,391</td><td>12</td><td>13,513</td><td>2</td></tr><tr><td>Written options</td><td>14,206</td><td>–</td><td>9,947</td><td>–</td></tr><tr><td>Purchased options</td><td>13,093</td><td>372</td><td>6,796</td><td>184</td></tr><tr><td> Credit derivatives</td><td>3,046,381</td><td>7,493</td><td>1,497,869</td><td>756</td></tr><tr><td>Credit risk before cash collateral</td><td></td><td>47,413</td><td></td><td>30,728</td></tr><tr><td>Less: Cash collateral applied</td><td></td><td>12,751</td><td></td><td>7,289</td></tr><tr><td> Total derivative assets</td><td></td><td>$34,662</td><td></td><td>$23,439</td></tr></table>
<table><tr><td></td><td>2015</td><td> 2014</td></tr><tr><td>Deferred tax assets related to:</td><td></td><td></td></tr><tr><td>Accrued compensation and benefits</td><td>$961</td><td>$965</td></tr><tr><td>Pensions<sup>(a)</sup></td><td>4,462</td><td>4,317</td></tr><tr><td>Other postretirement benefit obligations</td><td>375</td><td>386</td></tr><tr><td>Contract accounting methods</td><td>1,039</td><td>989</td></tr><tr><td>Foreign company operating losses and credits</td><td>70</td><td>59</td></tr><tr><td>Other</td><td>434</td><td>198</td></tr><tr><td>Valuation allowance<sup>(b)</sup></td><td>-76</td><td>-9</td></tr><tr><td>Deferred tax assets, net</td><td>7,265</td><td>6,905</td></tr><tr><td>Deferred tax liabilities related to:</td><td></td><td></td></tr><tr><td>Goodwill and purchased intangibles</td><td>474</td><td>454</td></tr><tr><td>Property, plant and equipment</td><td>457</td><td>514</td></tr><tr><td>Exchanged debt securities and other<sup>(c)</sup></td><td>409</td><td>485</td></tr><tr><td>Deferred tax liabilities</td><td>1,340</td><td>1,453</td></tr><tr><td>Net deferred tax assets<sup>(d)</sup></td><td>$5,925</td><td>$5,452</td></tr></table>
<table><tr><td></td><td>12/12</td><td>12/13</td><td>12/14</td><td>12/15</td><td>12/16</td><td>12/17</td></tr><tr><td>Royal Caribbean Cruises Ltd.</td><td>100.00</td><td>142.11</td><td>251.44</td><td>313.65</td><td>260.04</td><td>385.47</td></tr><tr><td>S&P 500</td><td>100.00</td><td>132.39</td><td>150.51</td><td>152.59</td><td>170.84</td><td>208.14</td></tr><tr><td>Dow Jones US Travel & Leisure</td><td>100.00</td><td>145.48</td><td>169.28</td><td>179.27</td><td>192.85</td><td>238.77</td></tr></table>

Question: What's the difference of Total derivative assets between 2006 and 2007? (in million)
Answer: 11223
Reasoning program: subtract(34662,23439)