|                                                                 |   | Year Ended December 31, |   |
|----------------------------------------------------------------------|--------|-------------------------|--------|
|                                                                 |   | 2006                    |   |   | 2007 (1) |   |   | 2008 (1) |   |   | 2009 (1) |   |   | 2010 (1) |   |
|                                                                 |   |                    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net Income                                                           |   | $                       | 207    |   |   | $ | 287 |   |   | $ | 343 |   |   | $ | 230 |   |   | $ | 300 |   |
| Equity in earnings of unconsolidatedaffiliates, net of distributions |   |                    | (5     | ) |   |   | (13 | ) |   |   | (51 | ) |   |   | (3 | ) |   |   | 13 |   |
| Income taxes                                                         |   |                    | 116    |   |   |   | 173 |   |   |   | 228 |   |   |   | 146 |   |   |   | 187 |   |
| Capitalized interest                                                 |   |                    | (6     | ) |   |   | (12 | ) |   |   | (5 | ) |   |   | (2 | ) |   |   | (7 | ) |
|                                                                 |   |                    | 312    |   |   |   | 435 |   |   |   | 515 |   |   |   | 371 |   |   |   | 493 |   |
|                                                                 |   |                    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Fixed charges, as defined:                                           |   |                    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
|                                                                 |   |                    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Interest                                                             |   |                    | 167    |   |   |   | 187 |   |   |   | 206 |   |   |   | 213 |   |   |   | 208 |   |
| Capitalized interest                                                 |   |                    | 6      |   |   |   | 12 |   |   |   | 5 |   |   |   | 2 |   |   |   | 7 |   |
| Interest component of rentals charged tooperating expense            |   |                    | 17     |   |   |   | 14 |   |   |   | 13 |   |   |   | 12 |   |   |   | 25 |   |
| Total fixed charges                                                  |   |                    | 190    |   |   |   | 213 |   |   |   | 224 |   |   |   | 227 |   |   |   | 240 |   |
|                                                                 |   |                    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Earnings, as defined                                                 |   | $                       | 502    |   |   | $ | 648 |   |   | $ | 739 |   |   | $ | 598 |   |   | $ | 733 |   |
|                                                                 |   |                    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Ratio of earnings to fixed charges                                   |   |                    | 2.64   |   |   |   | 3.04 |   |   |   | 3.30 |   |   |   | 2.63 |   |   |   | 3.05 |   |

| (1) | Excluded from the computation of fixed charges for the years ended December 31, 2007, 2008, 2009 and 2010 is interest income of $2 million, $1 million, $-0- and $1 million, respectively, which is included in income tax expense. |
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