<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CONDENSED
CONSOLIDATED BALANCE SHEETS AND STATEMENTS OF EARNINGS AND IS QUALIFIED IN ITS
ENTIRETY BE REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-END>                               JUN-30-1997
<CASH>                                           4,213
<SECURITIES>                                    20,163
<RECEIVABLES>                                   85,075
<ALLOWANCES>                                       674
<INVENTORY>                                     18,517
<CURRENT-ASSETS>                               143,153
<PP&E>                                         525,770
<DEPRECIATION>                                 213,740
<TOTAL-ASSETS>                                 527,296
<CURRENT-LIABILITIES>                           86,633
<BONDS>                                        177,251
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         3,091
<OTHER-SE>                                     205,512
<TOTAL-LIABILITY-AND-EQUITY>                   527,296
<SALES>                                         34,611
<TOTAL-REVENUES>                               203,633
<CGS>                                           24,377
<TOTAL-COSTS>                                  136,857
<OTHER-EXPENSES>                                44,122
<LOSS-PROVISION>                                     2
<INTEREST-EXPENSE>                               6,824
<INCOME-PRETAX>                                 20,536
<INCOME-TAX>                                     7,692
<INCOME-CONTINUING>                             12,844
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    12,844
<EPS-PRIMARY>                                      .52
<EPS-DILUTED>                                      .52