
<TABLE> <S> <C>

<PAGE>

<ARTICLE> 5
<MULTIPLIER>    1,000

<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               DEC-31-1997
<CASH>                                           2,519
<SECURITIES>                                         0
<RECEIVABLES>                                   81,203
<ALLOWANCES>                                   (5,898)
<INVENTORY>                                     15,466
<CURRENT-ASSETS>                               121,552
<PP&E>                                         736,668
<DEPRECIATION>                               (305,190)
<TOTAL-ASSETS>                                 635,808
<CURRENT-LIABILITIES>                           73,812
<BONDS>                                        118,401
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                        23,579
<OTHER-SE>                                     322,966
<TOTAL-LIABILITY-AND-EQUITY>                   635,808
<SALES>                                        460,973
<TOTAL-REVENUES>                               472,812
<CGS>                                          394,764
<TOTAL-COSTS>                                  438,346
<OTHER-EXPENSES>                                 1,783
<LOSS-PROVISION>                                 1,326
<INTEREST-EXPENSE>                               7,713
<INCOME-PRETAX>                                 23,644
<INCOME-TAX>                                     7,042
<INCOME-CONTINUING>                             16,602
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    16,602
<EPS-PRIMARY>                                     0.71<F1>
<EPS-DILUTED>                                     0.70
<FN>
<F1>ESP-PRIMARY IS EQUAL TO ESP-BASIC
</FN>


</TABLE>
