|                                                                                                           |   | Year      Ended December 31,             |   |
|----------------------------------------------------------------------------------------------------------------|--------|------------------------------------------|--------|
|                                                                                                           |   |       2004 |   |   |       2005 |   |   |       2006 |   |   |        2007      (1) |   |   |        2008      (1) |   |
|                                                                                                           |   |                                     |   |   |   |   |   |   |   |   |   |   |   |   |   |
|  Net      Income                                                                                          |   | $                                        | 144    |   |   | $ | 193 |   |   | $ | 207 |   |   | $ | 287 |   |   | $ | 343 |   |
|  Income      taxes                                                                                        |   |                                     | 87     |   |   |   | 116 |   |   |   | 116 |   |   |   | 173 |   |   |   | 228 |   |
|  Capitalized      interest                                                                                |   |                                     | (2     | ) |   |   | (1 | ) |   |   | (6 | ) |   |   | (12 | ) |   |   | (14 | ) |
|                                                                                                           |   |                                     | 229    |   |   |   | 308 |   |   |   | 317 |   |   |   | 448 |   |   |   | 557 |   |
|                                                                                                           |   |                                     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
|  Fixed      charges, as defined:                                                                          |   |                                     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
|                                                                                                           |   |                                     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Interest expense                                                                                               |   |                                     | 178    |   |   |   | 176 |   |   |   | 167 |   |   |   | 187 |   |   |   | 213 |   |
| Capitalized    interest                                                                                        |   |                                     | 2      |   |   |   | 1 |   |   |   | 6 |   |   |   | 12 |   |   |   | 14 |   |
| Interest component of rentals      charged             to operating expense |   |                                     | 10     |   |   |   | 11 |   |   |   | 17 |   |   |   | 14 |   |   |   | 13 |   |
| Total fixedcharges                                                                                             |   |                                     | 190    |   |   |   | 188 |   |   |   | 190 |   |   |   | 213 |   |   |   | 240 |   |
|                                                                                                           |   |                                     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
|  Earnings,      as defined                                                                                |   | $                                        | 419    |   |   | $ | 496 |   |   | $ | 507 |   |   | $ | 661 |   |   | $ | 797 |   |
|                                                                                                           |   |                                     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
|  Ratio      of earnings to fixed charges                                                                  |   |                                     | 2.20   |   |   |   | 2.64 |   |   |   | 2.67 |   |   |   | 3.10 |   |   |   | 3.32 |   |

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