|                                                                          |   |                     |    |   Twelve |   |  Three        |       |
|-------------------------------------------------------------------------------|--------|--------------------------|---------|--------------------|--------|--------------------|------------|
|                                                                          |   |                     |    |   Months |   |   Months |       |
|                                                                          |   | Years Ended December 31, |    |   Ended  |   |   Ended  |       |
|                                                                          |   | 2006                     |    | 2007               |   |               |  2008 |   | 2009 |   | 2010 |   |    3/31/2011 |   |    3/31/2011 |   |
| EARNINGS                                                                      |   |                |    |          |   |               |       |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Income Before Income Taxes                                                    |   | $                        | 282,865 |               | $      | 195,613            |       | $ | 166,801 |   | $ | 201,263 |   | $ | 210,898  |   | $ |  165,233  |   | $  |  67,764  |   |
| Fixed Charges (as below)                                                      |   |                     | 151,874 |               |   | 178,067            |       |   | 225,573 |   |   | 215,640 |   |   | 217,500  |   |   |  218,522  |   |   |  55,481  |   |
| Total Earnings                                                                |   | $                        | 434,739 |               | $      | 373,680            |       | $ | 392,374 |   | $ | 416,903 |   | $ | 428,398  |   | $  |  383,755  |   | $  |  123,245  |   |
|                                                                          |   |                     |    |               |   |               |       |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| FIXED CHARGES                                                                 |   |                     |    |               |   |               |       |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Interest Expense                                                              |   | $                        | 129,106 |               | $      | 165,405            |       | $ | 209,733 |   | $ | 202,426 |   | $ | 207,649  |   | $  |  208,861  |   | $  |  52,939  |   |
| Credit for Allowance for Borrowed Funds Used    During Construction |   |                     | 17,668  |               |   | 6,962              |       |   | 9,040 |   |   | 6,014 |   |   | 2,251  |   |   |  2,061  |   |   |  642  |   |
| Estimated Interest Element in Lease Rentals                                   |   |                     | 5,100   |               |   | 5,700              |       |   | 6,800 |   |   | 7,200 |   |   | 7,600  |   |   |  7,600  |   |   |  1,900  |   |
| Total Fixed Charges                                                           |   | $                        | 151,874 |               | $      | 178,067            |       | $ | 225,573 |   | $ | 215,640 |   | $ | 217,500  |   | $  |  218,522  |   | $  |  55,481  |   |
|                                                                          |   |                     |    |               |   |               |       |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Ratio of Earnings to Fixed Charges                                            |   |                     | 2.86    |               |   | 2.09               |       |   | 1.73 |   |   | 1.93 |   |   | 1.96 |   |   |  1.75  |   |   |  2.22  |   |