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|                                                                                             |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| Computation of Ratio of Earnings to Fixed Charges and Ratio of Earnings to Fixed            |
| Charges and Preferred Stock Dividends                                                       |
|                                                                                        |   | Year Ended December 31, |
|                                                                                        |   | 2012 |   | 2011 |   | 2010 |   | 2009 |   | 2008 |
| (millions)                                                                                  |   |   |   |   |   |   |   |   |   |   |
| Income (Loss) From Continuing Operations Before Income Tax and Income From Equity Investees |   | $ | 1,170 |  |   | $ | 309 |  |   | $ | 730 |  |   | $ | (410 | ) |   | $ | 1,598 |  |
| Add (Deduct)                                                                                |   |   |   |   |   |   |   |   |   |   |
| Fixed Charges                                                                               |   | 288 |  |   | 207 |  |   | 148 |  |   | 136 |  |   | 109 |  |
| Capitalized Interest                                                                        |   | (151 | ) |   | (132 | ) |   | (67 | ) |   | (45 | ) |   | (33 | ) |
| Distributed Income From Equity Investees                                                    |   | 204 |  |   | 225 |  |   | 139 |  |   | 92 |  |   | 221 |  |
| Earnings as Defined                                                                         |   | $ | 1,511 |  |   | $ | 609 |  |   | $ | 950 |  |   | $ | (227 | ) |   | $ | 1,895 |  |
|                                                                                        |   |   |   |   |   |   |   |   |   |   |
| Net Interest Expense                                                                        |   | 125 |  |   | 65 |  |   | 72 |  |   | 84 |  |   | 69 |  |
| Capitalized Interest                                                                        |   | 151 |  |   | 132 |  |   | 67 |  |   | 45 |  |   | 33 |  |
| Interest Portion of Rental Expense                                                          |   | 12 |  |   | 10 |  |   | 9 |  |   | 7 |  |   | 7 |  |
| Fixed Charges as Defined                                                                    |   | $ | 288 |  |   | $ | 207 |  |   | $ | 148 |  |   | $ | 136 |  |   | $ | 109 |  |
|                                                                                        |   |   |   |   |   |   |   |   |   |   |
| Ratio of Earnings to Fixed Charges (1)                                                      |   | 5.2 |  |   | 2.9 |  |   | 6.4 |  |   | — |  |   | 17.4 |  |
|                                                                                        |   |   |   |   |   |   |   |   |   |   |
| Amount by Which Earnings Were Insufficient to Cover Fixed Charges                           |   | $ | — |  |   | $ | — |  |   | $ | — |  |   | $ | (363 | ) |   | $ | — |  |

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| (1) | The ratio of earnings to fixed charges and preferred stock dividends is the same as the ratio of earnings to fixed charges for the periods presented because no shares of preferred stock were outstanding during the periods. |