<TABLE> <S> <C>

<ARTICLE>                                          5
<RESTATED>
<MULTIPLIER>                                                    1,000
       
<S>                                                  <C>                  <C>                           <C>
<PERIOD-TYPE>                                                   3-mos                       6-mos                      9-mos
<FISCAL-YEAR-END>                                         Dec-31-1996                 Dec-31-1996                Dec-31-1996
<PERIOD-END>                                              Mar-31-1996                 Jun-30-1996                Sep-30-1996
<CASH>                                                         38,044                      31,205                     32,937
<SECURITIES>                                                        0                           0                          0
<RECEIVABLES>                                                 139,778                     120,982                    107,232
<ALLOWANCES>                                                        0                           0                          0
<INVENTORY>                                                     6,618                       6,806                     14,080
<CURRENT-ASSETS>                                              199,301                     168,233                    165,355
<PP&E>                                                      1,807,328                   1,862,023                  1,973,664
<DEPRECIATION>                                                689,218                     717,319                    751,857
<TOTAL-ASSETS>                                              1,364,512                   1,358,892                  1,432,383
<CURRENT-LIABILITIES>                                         136,534                     137,984                    133,193
<BONDS>                                                       546,535                     538,882                    604,583
<PREFERRED-MANDATORY>                                               0                           0                          0
<PREFERRED>                                                         0                           0                          0
<COMMON>                                                        6,280                       6,296                      6,304
<OTHER-SE>                                                    571,227                     569,960                    577,915
<TOTAL-LIABILITY-AND-EQUITY>                                1,364,512                   1,358,892                  1,432,383
<SALES>                                                       136,575                     248,864                    358,795
<TOTAL-REVENUES>                                              136,575                     248,864                    358,795
<CGS>                                                          16,200                      22,457                     26,974
<TOTAL-COSTS>                                                  95,471                     189,510                    277,607
<OTHER-EXPENSES>                                               (1,155)                     (1,919)                    (7,151)
<LOSS-PROVISION>                                                    0                           0                          0
<INTEREST-EXPENSE>                                             11,446                      22,683                     33,478
<INCOME-PRETAX>                                                27,084                      30,227                     43,864
<INCOME-TAX>                                                    8,772                      14,849                     21,028
<INCOME-CONTINUING>                                            18,312                      15,378                     22,836
<DISCONTINUED>                                                      0                           0                          0
<EXTRAORDINARY>                                                     0                           0                          0
<CHANGES>                                                           0                           0                          0
<NET-INCOME>                                                   18,312                      15,378                     22,836
<EPS-PRIMARY>                                                    0.29 <F1>                   0.24 <F1>                  0.36 <F1>
<EPS-DILUTED>                                                    0.29 <F1>                   0.24 <F1>                  0.36 <F1>

<FN>
<F1> Earnings per share has been restated to reflect the Company's adoption of
     Statement of Financial Accounting Standards No. 128, "Earnings Per Share."
</FN>
        


</TABLE>