Exhibit 12

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

The ratio of earnings to fixed charges is calculated using the Securities and Exchange Commission guidelines.



|                                                              |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|------------------------------------------------------------- |  | ----------------------- | --- | ---- | - | ---- |  | ---- | --- | ---- | - | --- |  | - | ---
|                                                              |  | Year Ended December 31,
|                                                              |  | 2009                    |     | 2008 |   | 2007 |  | 2006 |     | 2005
|                                                              |  | (dollars in millions)  
|Earnings as defined for fixed charges calculation             |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|Add:                                                          |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|Pre-tax income                                                |  | $                       | 317 |      | $ | 408  |  | $    | 386 |      | $ | 200 |  | $ | 325
|Fixed charges                                                 |  |                         | 165 |      |   | 140  |  |      | 130 |      |   | 145 |  |   | 126
|Deduct:                                                       |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|Interest capitalized(a)                                       |  |                         | 13  |      |   | 10   |  |      | 11  |      |   | 16  |  |   | 8  
|                                                              |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|Total earnings (as defined for the Fixed Charges calculation) |  | $                       | 469 |      | $ | 538  |  | $    | 505 |      | $ | 329 |  | $ | 443
|                                                              |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|Fixed charges:                                                |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|Interest on debt, including capitalized portions              |  | $                       | 157 |      | $ | 133  |  | $    | 120 |      | $ | 138 |  | $ | 118
|Estimate of interest within rental expense                    |  |                         | 8   |      |   | 7    |  |      | 10  |      |   | 7   |  |   | 8  
|                                                              |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|Total fixed charges                                           |  | $                       | 165 |      | $ | 140  |  | $    | 130 |      | $ | 145 |  | $ | 126
|                                                              |  |                         |     |      |   |      |  |      |     |      |   |     |  |   |    
|Ratio of earnings to fixed charges                            |  |                         | 2.9 |      |   | 3.8  |  |      | 3.9 |      |   | 2.3 |  |   | 3.5



|(a) | Excludes equity costs related to AFUDC that are included in Other Income and Expenses in the Consolidated Statements of Operations.
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