<ARTICLE> 5 <MULTIPLIER> 1,000 <PERIOD-TYPE> YEAR <FISCAL-YEAR-END> SEP-30-1997 <PERIOD-START> OCT-01-1996 <PERIOD-END> SEP-30-1997 <CASH> 27,963 <SECURITIES> 323,510 <RECEIVABLES> 100,005 <ALLOWANCES> 1,308 <INVENTORY> 19,639 <CURRENT-ASSETS> 158,004 <PP&E> 1,160,881 <DEPRECIATION> 621,856 <TOTAL-ASSETS> 1,033,595 <CURRENT-LIABILITIES> 95,167 <BONDS> 0 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 2,677 <OTHER-SE> 777,903 <TOTAL-LIABILITY-AND-EQUITY> 1,033,595 <SALES> 506,422 <TOTAL-REVENUES> 517,859 <CGS> 376,886 <TOTAL-COSTS> 376,886 <OTHER-EXPENSES> 9,346 <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 4,212 <INCOME-PRETAX> 127,415 <INCOME-TAX> 45,511 <INCOME-CONTINUING> 84,186 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 84,186 <EPS-PRIMARY> 1.69 <EPS-DILUTED> 1.69