|                                                                                                                             |   | Year                  Ended December                  31, |    |
|----------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------------------------------------|---------|
|                                                                                                                             |   | 2003                                                      |    | 2004 |   | 2005 |   | 2006 |   | 2007 |   |
| EARNINGS                                                                                                                         |   |                                                 |    |    |   |    |   |    |   |    |   |
| Income                  Before Income Taxes                                                                                      |   | $                                                         | 246,809 |   | $ | 207,929 |   | $ | 199,259 |   | $ | 286,422 |   | $ | 387,473 |   |
| Fixed                  Charges (as below)                                                                                        |   |                                                      | 58,771  |   |   | 61,742 |   |   | 63,665 |   |   | 74,155 |   |   | 79,400 |   |
| Total                  Earnings                                                                                                  |   | $                                                         | 305,580 |   | $ | 269,671 |   | $ | 262,924 |   | $ | 360,577 |   | $ | 466,873 |   |
|                                                                                                                             |   |                                                      |    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| FIXED CHARGES                                                                                                               |   |                                                      |    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Interest                Expense                                                                                                  |   | $                                                         | 50,948  |   | $ | 54,246 |   | $ | 59,539 |   | $ | 66,100 |   | $ | 69,625 |   |
| Credit                  for Allowance for Borrowed Funds Used During                                      Construction |   |                                                      | 5,123   |   |   | 4,996 |   |   | 1,526 |   |   | 5,955 |   |   | 7,275 |   |
| Estimated                  Interest Element in Lease Rentals                                                                     |   |                                                      | 2,700   |   |   | 2,500 |   |   | 2,600 |   |   | 2,100 |   |   | 2,500 |   |
| Total                  Fixed                  Charges                                                                            |   | $                                                         | 58,771  |   | $ | 61,742 |   | $ | 63,665 |   | $ | 74,155 |   | $ | 79,400 |   |
|                                                                                                                             |   |                                                      |    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Ratio                  of Earnings to Fixed                  Charges                                                             |   |                                                      | 5.19    |   |   | 4.36 |   |   | 4.12 |   |   | 4.86 |   |   | 5.88 |   |