<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED FINANCIAL STATEMENTS AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE
TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> 9-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-START> JAN-01-2000
<PERIOD-END> SEP-30-2000
<CASH> 2,885
<SECURITIES> 0
<RECEIVABLES> 50,967
<ALLOWANCES> 0
<INVENTORY> 0
<CURRENT-ASSETS> 55,257
<PP&E> 1,144,109
<DEPRECIATION> (571,454)
<TOTAL-ASSETS> 683,461
<CURRENT-LIABILITIES> 57,249
<BONDS> 0
0
0
<COMMON> 500
<OTHER-SE> 346,329
<TOTAL-LIABILITY-AND-EQUITY> 683,461
<SALES> 188,160
<TOTAL-REVENUES> 188,367
<CGS> 0
<TOTAL-COSTS> 100,531
<OTHER-EXPENSES> 2,572
<LOSS-PROVISION> 0
<INTEREST-EXPENSE> 2,636
<INCOME-PRETAX> 84,132
<INCOME-TAX> (29,450)
<INCOME-CONTINUING> 54,682
<DISCONTINUED> 0
<EXTRAORDINARY> 0
<CHANGES> 0
<NET-INCOME> 54,682
<EPS-BASIC> 1.35
<EPS-DILUTED> 1.34
</TABLE>