<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<RESTATED>
<MULTIPLIER> 1,000
<S> <C> <C> <C> <C>
<PERIOD-TYPE> 12-MOS 9-MOS 6-MOS 3-MOS
<FISCAL-YEAR-END> DEC-31-1997 DEC-31-1997 DEC-31-1997 DEC-31-1997
<PERIOD-END> DEC-31-1997 SEP-30-1997 JUN-30-1997 MAR-31-1997
<CASH> 10,200 14,400 17,400 22,800
<SECURITIES> 0 0 0 0
<RECEIVABLES> 244,100 193,800 296,500 299,900
<ALLOWANCES> 0 0 0 0
<INVENTORY> 9,900 10,700 13,000 10,300
<CURRENT-ASSETS> 288,900 302,000 374,400 373,600
<PP&E> 5,189,800 4,985,700 4,831,300 4,760,700
<DEPRECIATION> 3,598,400 3,519,500 3,447,000 3,387,800
<TOTAL-ASSETS> 1,924,800 1,788,600 1,758,700 1,746,500
<CURRENT-LIABILITIES> 359,500 327,700 326,600 386,900
<BONDS> 672,100 636,300 643,300 630,300
0 0 0 0
0 0 0 0
<COMMON> 1,000 1,000 1,000 1,000
<OTHER-SE> 504,500 444,800 399,000 348,000
<TOTAL-LIABILITY-AND-EQUITY> 1,924,800 1,788,600 1,758,700 1,746,500
<SALES> 3,306,600 2,672,500 1,868,000 1,104,500
<TOTAL-REVENUES> 3,333,900 2,693,000 1,883,100 1,106,400
<CGS> 492,500 358,800 237,200 117,900
<TOTAL-COSTS> 668,000 493,200 334,100 188,700
<OTHER-EXPENSES> 2,320,200 1,947,700 1,369,600 822,800
<LOSS-PROVISION> 0 0 0 0
<INTEREST-EXPENSE> 47,800 35,900 24,400 13,000
<INCOME-PRETAX> 234,600 169,500 123,800 67,200
<INCOME-TAX> (5,900) (4,100) 2,600 4,300
<INCOME-CONTINUING> 240,500 173,600 121,200 62,900
<DISCONTINUED> 0 0 0 0
<EXTRAORDINARY> 0 0 0 0
<CHANGES> 0 0 0 0
<NET-INCOME> 240,500 173,600 121,200 62,900
<EPS-BASIC> 2.47 1.78 1.25 0.65
<EPS-DILUTED> 2.46 1.78 1.25 0.65
</TABLE>