<ARTICLE> 5 <MULTIPLIER> 1,000 <PERIOD-TYPE> 6-MOS <FISCAL-YEAR-END> DEC-31-2000 <PERIOD-START> JAN-01-2000 <PERIOD-END> JUN-30-2000 <CASH> 39,901 <SECURITIES> 0 <RECEIVABLES> 145,477 <ALLOWANCES> 0 <INVENTORY> 4,745 <CURRENT-ASSETS> 199,311 <PP&E> 2,940,464 <DEPRECIATION> 1,659,437 <TOTAL-ASSETS> 1,569,663 <CURRENT-LIABILITIES> 193,068 <BONDS> 505,406 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 195,807 <OTHER-SE> 521,411 <TOTAL-LIABILITY-AND-EQUITY> 1,569,663 <SALES> 320,112 <TOTAL-REVENUES> 578,371 <CGS> 0 <TOTAL-COSTS> 455,084 <OTHER-EXPENSES> 0 <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 18,960 <INCOME-PRETAX> 104,327 <INCOME-TAX> 40,587 <INCOME-CONTINUING> 63,740 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 63,740 <EPS-BASIC> 1.14 <EPS-DILUTED> 1.12