<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONDENSED BALANCE SHEETS AND CONDENSED STATEMENTS OF INCOME AND NOTES TO
CONDENSED CONSOLIDATED FINANCIAL STATEMENTS ON PAGES 1 THROUGH 21 OF THE
COMPANY'S FORM 10-Q FOR THE NINE MONTH PERIOD ENDING SEPTEMBER 30, 2000, AND IS
QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<S> <C>
<PERIOD-TYPE> 9-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-END> SEP-30-2000
<CASH> 7,807
<SECURITIES> 0
<RECEIVABLES> 90,843
<ALLOWANCES> 0
<INVENTORY> 0
<CURRENT-ASSETS> 121,799
<PP&E> 2,272,093
<DEPRECIATION> 1,533,631
<TOTAL-ASSETS> 889,165
<CURRENT-LIABILITIES> 99,464
<BONDS> 414,447
0
0
<COMMON> 5,428
<OTHER-SE> 345,120
<TOTAL-LIABILITY-AND-EQUITY> 889,165
<SALES> 351,868
<TOTAL-REVENUES> 351,868
<CGS> 200,013
<TOTAL-COSTS> 212,605
<OTHER-EXPENSES> 77,911
<LOSS-PROVISION> 0
<INTEREST-EXPENSE> 28,221
<INCOME-PRETAX> 33,131
<INCOME-TAX> 4,387
<INCOME-CONTINUING> 28,744
<DISCONTINUED> 0
<EXTRAORDINARY> 192
<CHANGES> 0
<NET-INCOME> 28,936
<EPS-BASIC> .54
<EPS-DILUTED> .53
</TABLE>