<TABLE> <S> <C>

<ARTICLE> 5
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   YEAR                   YEAR                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1998             DEC-31-1997             DEC-31-1996
<PERIOD-END>                               DEC-31-1998             DEC-31-1997             DEC-31-1996
<CASH>                                          12,576                  15,619                  71,961
<SECURITIES>                                         0                       0                   9,990
<RECEIVABLES>                                   23,176                  46,680                  21,378
<ALLOWANCES>                                         0                       0                       0
<INVENTORY>                                        579                     456                     897
<CURRENT-ASSETS>                                39,621                  72,347                 105,687
<PP&E>                                         500,510                 310,122                 182,200
<DEPRECIATION>                                  68,881                  49,635                  33,463
<TOTAL-ASSETS>                                 475,684                 334,182                 254,947
<CURRENT-LIABILITIES>                           32,922                  16,875                   9,016
<BONDS>                                              0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                           524                     519                     513
<OTHER-SE>                                     361,064                 295,223                 221,220
<TOTAL-LIABILITY-AND-EQUITY>                   475,684                 334,182                 254,947
<SALES>                                        228,015                 190,257                 110,329
<TOTAL-REVENUES>                               228,015                 190,257                 110,329
<CGS>                                          102,166                  77,847                  59,770
<TOTAL-COSTS>                                  102,166                  77,847                  59,770
<OTHER-EXPENSES>                                20,191                  16,995                  11,576
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                                 481                     575                     895
<INCOME-PRETAX>                                 95,541                  89,836                  32,256
<INCOME-TAX>                                    34,720                  31,456                  11,586
<INCOME-CONTINUING>                             60,821                  58,380                  20,670
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                    60,821                  58,380                  20,670
<EPS-PRIMARY>                                     1.16                    1.13                    0.46
<EPS-DILUTED>                                     1.15                    1.11                    0.45
        

</TABLE>