December 31, 2012, 2011 and 2010 was $(30) million, $98 million and $65 million, respectively.
The cumulative tax benefit related to the adjustment for pension and other postretirement benefits at December 31, 2012 and 2011 was approximately $960 million and $990 million, respectively.
There was no tax (cost) benefit related to the change in the unrealized gain (loss) on marketable securities for the year ended December 31, 2012.
The tax (cost) benefit related to the change in the unrealized gain (loss) on marketable securities for the years ended December 31, 2011 and 2010 was $(0.2) million and $0.6 million, respectively.
The tax benefit related to the change in the unrealized gain (loss) on derivatives for the years ended December 31, 2012, 2011 and 2010 was $4 million, $19 million and $1 million, respectively.18.
Employee Savings Plan PPG’s Employee Savings Plan (“Savings Plan”) covers substantially all U. S.  employees.
The Company makes matching contributions to the Savings Plan, at management's discretion, based upon participants’ savings, subject to certain limitations.
For most participants not covered by a collective bargaining agreement, Company-matching contributions are established each year at the discretion of the Company and are applied to participant savings up to a maximum of 6% of eligible participant compensation.
For those participants whose employment is covered by a collective bargaining agreement, the level of Company-matching contribution, if any, is determined by the relevant collective bargaining agreement.
The Company-matching contribution was suspended from March 2009 through June 2010 as a cost savings measure in recognition of the adverse impact of the global recession.
Effective July 1, 2010, the Company match was reinstated at 50% on the first 6% of compensation contributed for most employees eligible for the Company-matching contribution feature.
This included the union represented employees in accordance with their collective bargaining agreements.
On January 1, 2011, the Company match was increased to 75% on the first 6% of compensation contributed by these eligible employees and this level was maintained throughout 2012.
Compensation expense and cash contributions related to the Company match of participant contributions to the Savings Plan for 2012, 2011 and 2010 totaled $28 million, $26 million and $9 million, respectively.
A portion of the Savings Plan qualifies under the Internal Revenue Code as an Employee Stock Ownership Plan.
As a result, the dividends on PPG shares held by that portion of the Savings Plan totaling $18 million, $20 million and $24 million for 2012, 2011 and 2010, respectively, were tax deductible to the Company for U. S.  Federal tax purposes.
## Table 0 ##
20.
Stock-Based Compensation The Company’s stock-based compensation includes stock options, restricted stock units (“RSUs”) and grants of contingent shares that are earned based on achieving targeted levels of total shareholder return.
All current grants of stock options, RSUs and contingent shares are made under the PPG Industries, Inc.
Amended and Restated Omnibus Incentive Plan (“PPG Amended Omnibus Plan”), which was amended and restated effective April 21, 2011.
Shares available for future grants under the PPG Amended Omnibus Plan were 8.5 million as of December 31, 2012.
Total stock-based compensation cost was $73 million, $36 million and $52 million in 2012, 2011 and 2010, respectively.
Stock-based compensation expense increased year over year due to the increase in the expected payout percentage of the 2010 performance-based RSU grants and PPG's total shareholder return performance in 2012 in comparison with the Standard & Poors (S&P) 500 index, which has increased the expense related to outstanding grants of contingent shares.
The total income tax benefit recognized in the accompanying consolidated statement of income related to the stock-based compensation was $25 million, $13 million and $18 million in 2012, 2011 and 2010, respectively.
Stock Options PPG has outstanding stock option awards that have been granted under two stock option plans: the PPG Industries, Inc.  Stock Plan (“PPG Stock Plan”) and the PPG Amended Omnibus Plan.
Under the PPG Amended Omnibus Plan and the PPG Stock Plan, certain employees of the Company have been granted options to purchase shares of common stock at prices equal to the fair market value of the shares on the date the options were granted.
The options are generally exercisable beginning from six to 48 months after being granted and have a maximum term of 10 years.
Upon exercise of a stock option, shares of Company stock are issued from treasury stock.
The PPG Stock Plan includes a restored option provision for options originally granted prior to January 1, 2003 that allows an optionee to exercise options and satisfy the option cost by certifying ownership of mature shares of PPG common stock with a market value equal to the option cost.
The fair value of stock options issued to employees is measured on the date of grant and is recognized as expense over the requisite service period.
PPG estimates the fair value of stock options using the Black-Scholes option pricing model.
The riskfree interest rate is determined by using the U. S.  Treasury yield
Xcel Energy believes these authorizations are adequate and will seek additional authorization when necessary, however, there can be no assurance that additional authorization will be granted on the timeframe or in the amounts requested.
The FERC has granted a blanket authorization for certain intra-system financings involving holding companies.
In addition, Xcel Energy’s utility subsidiaries have received FERC authorization through June 30, 2008 to engage in intrasystem financings, including through the money pool, in amounts ranging from $250 million for each of NSP-Minnesota and PSCo, to $100 million for SPS and $75 million for NSP-Wisconsin.
Stockholder Protection Rights Agreement — In June 2001, Xcel Energy adopted a Stockholder Protection Rights Agreement.
Each share of Xcel Energy’s common stock includes one shareholder protection right.
Under the agreement’s principal provision, if any person or group acquires 15 percent or more of Xcel Energy’s outstanding common stock, all other shareholders of Xcel Energy would be entitled to buy, for the exercise price of $95 per right, common stock of Xcel Energy having a market value equal to twice the exercise price, thereby substantially diluting the acquiring person’s or group’s investment.
The rights may cause substantial dilution to a person or group that acquires 15 percent or more of Xcel Energy’s common stock.
The rights should not interfere with a transaction that is in the best interests of Xcel Energy and its shareholders because the rights can be redeemed prior to a triggering event for $0.01 per right.9.
Share-Based Compensation Effective Jan.  1, 2006, Xcel Energy adopted the provisions of SFAS No.123(R), which requires the measurement and recognition of compensation expense in an amount equal to the fair value of share-based payment awards granted to employees and directors including stock option awards, restricted stock, restricted stock units and performance share awards.
Xcel Energy previously applied the provisions of Accounting Principles Board Opinion No.25 — ‘‘Accounting for Stock Issued to Employees’’ and related Interpretations in order to provide the required pro forma disclosures under SFAS No.123, ‘‘Accounting for Share-based Compensation,’’ (‘‘SFAS No.123’’).
Xcel Energy adopted SFAS No.123(R) using the modified prospective transition method.
Accordingly, in 2006, Xcel Energy recorded share based compensation expense for awards granted prior to but not yet vested as of Jan, 1, 2006 as if the fair value method required for pro forma disclosure under SFAS No.123 were in effect for expense recognition purposes.
The pro forma information for share based compensation in 2005 was as follows:
## Table 1 ##
Stock Options — Xcel Energy has incentive compensation plans under which stock options and other performance incentives are awarded to key employees.
In the past, Xcel Energy issued stock options, but has not granted stock options since December 2001.
The weighted average number of common and potentially dilutive shares outstanding used to calculate Xcel Energy’s earnings per share include the dilutive effect of stock options and other stock awards based on the treasury stock method.
The options normally have a term of 10 years and generally become exercisable from three to five years after grant date or upon specified circumstances.
Activity in stock options was as follows for the years ended Dec.  31:
## Table 2 ##
Commodity Price Risk — Xcel Energy’s utility subsidiaries are exposed to commodity price risk in their electric and natural gas operations.
Commodity price risk is managed by entering into long- and short-term physical purchase and sales contracts for electric capacity, energy and other energy-related products and for various fuels used for generation of electricity and in the natural gas utility operations.
Commodity risk is also managed through the use of financial derivative instruments.
Xcel Energy’s utility subsidiaries utilize these derivative instruments to reduce the volatility in the cost of commodities acquired on behalf of its retail customers even though regulatory jurisdiction may provide for recovery of actual costs.
The use of derivative instruments is done consistently with the state regulatory cost-recovery mechanism.
Xcel Energy’s risk-management policy allows it to manage commodity price risk within each rate-regulated operation to the extent such exposure exists.
Short-Term Wholesale and Commodity Trading Risk — Xcel Energy’s utility subsidiaries conduct various short-term wholesale and commodity trading activities, including the purchase and sale of electric capacity and energy and other energy-related instruments.
Xcel Energy’s risk-management policy allows management to conduct these activities within guidelines and limitations as approved by our risk-management committee, which is made up of management personnel not directly involved in the activities governed by this policy.
Interest Rate Risk — Xcel Energy and its subsidiaries are subject to the risk of fluctuating interest rates in the normal course of business.
Xcel Energy’s risk-management policy allows interest rate risk to be managed through the use of fixed-rate debt, floating-rate debt and interest rate derivatives such as swaps, caps, collars and put or call options.
Types of and Accounting for Derivative Instruments Xcel Energy and its subsidiaries use derivative instruments in connection with its utility commodity price, interest rate, short-term wholesale and commodity trading activities, including forward contracts, futures, swaps and options.
Qualifying hedging relationships are designated as either a hedge of a forecasted transaction or future cash flow (cash flow hedge), or a hedge of a recognized asset, liability or firm commitment (fair value hedge).
The types of qualifying hedging transactions that Xcel Energy and its subsidiaries are currently engaged in are discussed below.
Cash Flow Hedges Commodity Cash Flow Hedges — Xcel Energy’s utility subsidiaries enter into derivative instruments to manage variability of future cash flows from changes in commodity prices.
These derivative instruments are designated as cash flow hedges for accounting purposes.
At Dec.  31, 2007, Xcel Energy had various commodity-related contracts classified as cash flow hedges extending through December 2009.
At Dec.  31, 2007, Xcel Energy had $0.5 million in accumulated other comprehensive income related to commodity cash flow hedge contracts that is expected to be recognized in earnings during the next 12 months as the hedged transactions settle.
Xcel Energy had immaterial ineffectiveness related to commodity cash flow hedges during 2007 and 2006.
Interest Rate Cash Flow Hedges — Xcel Energy and its subsidiaries enter into various instruments that effectively fix the interest payments on certain floating rate debt obligations or effectively fix the yield or price on a specified benchmark interest rate for a specific period.
These derivative instruments are designated as cash flow hedges for accounting purposes.
At Dec.  31, 2007, Xcel Energy had net losses related to interest rate swaps/locks of approximately $0.4 million in accumulated other comprehensive income that is expected to be recognized in earnings during the next 12 months.
Xcel Energy had immaterial ineffectiveness related to interest rate cash flow hedges during 2007 and no ineffectiveness related to interest rate cash flow hedges during 2006.
The following table shows the major components of the derivative instruments valuation in the consolidated balance sheets at Dec.  31:
## Table 3 ##
The Articles of Incorporation of Xcel Energy place restrictions on the amount of common stock dividends it can pay when preferred stock is outstanding.
Under the provisions, dividend payments may be restricted if Xcel Energy’s capitalization ratio (on a holding company basis only, not on a consolidated basis) is less than 25 percent.
For these purposes, the capitalization ratio is equal to common stock plus surplus, divided by the sum of common stock plus surplus plus long-term debt.
Based on this definition, Xcel Energy’s capitalization ratio at Dec.  31, 2007, was 85 percent.
Therefore, the restrictions do not place any effective limit on Xcel Energy’s ability to pay dividends.
Capital Sources Xcel Energy expects to meet future financing requirements by periodically issuing short-term debt, long-term debt, common stock, preferred securities and hybrid securities to maintain desired capitalization ratios.
Short-Term Funding Sources — Historically, Xcel Energy has used a number of sources to fulfill short-term funding needs, including operating cash flow, notes payable, commercial paper and bank lines of credit.
The amount and timing of short-term funding needs depend in large part on financing needs for construction expenditures, working capital and dividend payments.
As of Feb.  15, 2008, Xcel Energy and its utility subsidiaries had the following committed credit facilities available to meet its liquidity needs:
## Table 4 ##
* Includes outstanding commercial paper and letters of credit.
Operating cash flow as a source of short-term funding is affected by such operating factors as weather; regulatory requirements, including rate recovery of costs; environmental regulation compliance; changes in the trends for energy prices; supply and operational uncertainties and other changes in working capital, all of which are difficult to predict.
See further discussion of such factors under Statement of Operations Analysis.
Short-term borrowing as a source of funding is affected by regulatory actions and access to reasonably priced capital markets.
For additional information on Xcel Energy’s short-term borrowing arrangements, see Note 4 to the consolidated financial statements.
Access to reasonably priced capital markets is dependent in part on credit agency reviews and ratings.
The following ratings reflect the views of Moody’s, Standard & Poor’s, and Fitch.
A security rating is not a recommendation to buy, sell or hold securities, and is subject to revision or withdrawal at any time by the rating agency.
As of Feb.  15, 2008, the following represents the credit ratings assigned to various Xcel Energy companies:

<table><tr><td>(Millions)</td><td>2012</td><td>2011</td><td>2010</td></tr><tr><td>Royalty income</td><td>$51</td><td>$55</td><td>$58</td></tr><tr><td>Share of net earnings of equity affiliates (See Note 5)</td><td>11</td><td>37</td><td>45</td></tr><tr><td>Gain on sale of assets</td><td>4</td><td>12</td><td>8</td></tr><tr><td>Other</td><td>83</td><td>73</td><td>69</td></tr><tr><td>Total</td><td>$149</td><td>$177</td><td>$180</td></tr></table>
<table><tr><td></td><td>2005 (Thousands of Dollars, except per share amounts)</td></tr><tr><td>Net income — as reported</td><td>$512,972</td></tr><tr><td>Less: Total share-based employee compensation expense determined under fair-value-based method for stock options, net of related tax effects</td><td>-1,180</td></tr><tr><td>Pro forma net income</td><td>$511,792</td></tr><tr><td>Earnings per share:</td><td></td></tr><tr><td>Basic — as reported</td><td>$1.26</td></tr><tr><td>Basic — pro forma</td><td>1.26</td></tr><tr><td>Diluted — as reported</td><td>1.23</td></tr><tr><td>Diluted — pro forma</td><td>1.23</td></tr></table>
<table><tr><td> </td><td colspan="2"> 2007</td><td colspan="2"> 2006</td><td colspan="2"> 2005</td></tr><tr><td> (Awards in thousands) </td><td>Awards</td><td> Average Price</td><td>Awards</td><td> Average Price</td><td>Awards</td><td> Average Price</td></tr><tr><td>Outstanding beginning of year</td><td>12,374</td><td>$27.36</td><td>13,576</td><td>$26.92</td><td>14,606</td><td>$26.67</td></tr><tr><td>Exercised</td><td>-266</td><td>19.18</td><td>-563</td><td>18.33</td><td>-152</td><td>17.30</td></tr><tr><td>Forfeited</td><td>-50</td><td>27.43</td><td>-89</td><td>26.98</td><td>-213</td><td>26.84</td></tr><tr><td>Expired</td><td>-2,511</td><td>29.37</td><td>-550</td><td>25.66</td><td>-665</td><td>23.71</td></tr><tr><td>Outstanding at end of year</td><td>9,547</td><td>27.19</td><td>12,374</td><td>27.36</td><td>13,576</td><td>26.92</td></tr><tr><td>Exercisable at end of year</td><td>9,547</td><td>27.19</td><td>12,374</td><td>27.36</td><td>13,529</td><td>26.91</td></tr></table>
<table><tr><td> </td><td colspan="2"> 2007</td><td colspan="2"> 2006</td></tr><tr><td> </td><td> Derivative Instruments Valuation — Assets</td><td> Derivative Instruments Valuation — Liabilities</td><td> Derivative Instruments Valuation — Assets</td><td> Derivative Instruments Valuation — Liabilities</td></tr><tr><td> </td><td colspan="4"> (Thousands of Dollars) </td></tr><tr><td>Long-term purchased power agreements</td><td>$426,774</td><td>$401,313</td><td>$478,853</td><td>$502,789</td></tr><tr><td>Electric and natural gas trading and hedging instruments</td><td>51,106</td><td>21,694</td><td>57,797</td><td>40,881</td></tr><tr><td>Interest rate hedging instruments</td><td>535</td><td>20,223</td><td>2,432</td><td>23,351</td></tr><tr><td>Total</td><td>$478,415</td><td>$443,230</td><td>$539,082</td><td>$567,021</td></tr></table>
<table><tr><td> </td><td> Facility</td><td> Drawn*</td><td> Available</td><td> Cash</td><td> Liquidity</td><td> Maturity</td></tr><tr><td> </td><td colspan="6"> (Million of Dollars) </td></tr><tr><td>NSP-Minnesota</td><td>$500</td><td>$323.4</td><td>$176.6</td><td>$8.7</td><td>$185.3</td><td>December 2011</td></tr><tr><td>PSCo</td><td>700</td><td>184.2</td><td>515.8</td><td>125.9</td><td>641.7</td><td>December 2011</td></tr><tr><td>SPS</td><td>250</td><td>103.0</td><td>147.0</td><td>0.3</td><td>147.3</td><td>December 2011</td></tr><tr><td>Xcel Energy — holding company</td><td>800</td><td>179.8</td><td>620.2</td><td>4.6</td><td>624.8</td><td>December 2011</td></tr><tr><td>Total</td><td>$2,250</td><td>$790.4</td><td>$1,459.6</td><td>$139.5</td><td>$1,599.1</td><td></td></tr></table>

Question: what was the change in millions of total stock-based compensation cost from 2010 to 2011?
Answer: -16.0