
<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED>
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   12-MOS                   12-MOS                   12-MOS
<FISCAL-YEAR-END>                          DEC-31-1995             DEC-31-1996             DEC-31-1997
<PERIOD-END>                               DEC-31-1995             DEC-31-1996             DEC-31-1997
<CASH>                                              62                   5,564                   7,338
<SECURITIES>                                    10,361                  72,512                  69,633
<RECEIVABLES>                                   11,390                  34,359                  45,991
<ALLOWANCES>                                       813                   1,462                   2,327
<INVENTORY>                                          0                       0                       0
<CURRENT-ASSETS>                                21,959                 116,284                 124,757
<PP&E>                                          15,873                  36,615                  75,550
<DEPRECIATION>                                   6,510                  11,756                  21,812
<TOTAL-ASSETS>                                  32,177                 147,011                 192,367
<CURRENT-LIABILITIES>                           11,146                  27,773                  43,007
<BONDS>                                          3,193                  10,144                   9,891
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                     12,867                       0                       0
<COMMON>                                           407                     571                     592
<OTHER-SE>                                       3,661                 107,959                 137,660
<TOTAL-LIABILITY-AND-EQUITY>                    32,177                 147,011                 192,367
<SALES>                                         54,933                 171,265                 279,057
<TOTAL-REVENUES>                                54,933                 171,265                 279,057
<CGS>                                           30,941                 104,142                 178,702
<TOTAL-COSTS>                                   50,171                 147,646                 245,910
<OTHER-EXPENSES>                               (2,964)                 (1,178)                 (3,476)
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                                 496                   1,160                   1,166
<INCOME-PRETAX>                                  7,230                  23,637                  35,457
<INCOME-TAX>                                     2,992                   9,773                  14,123
<INCOME-CONTINUING>                              4,238                  13,864                  21,334
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                     4,238                  13,864                  21,334
<EPS-PRIMARY>                                     0.08                    0.25                    0.37
<EPS-DILUTED>                                     0.08                    0.24                    0.35
        

</TABLE>
