<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED> 
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   3-MOS                   6-MOS                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-START>                             JAN-01-1997             JAN-01-1997             JAN-01-1997
<PERIOD-END>                               MAR-31-1997             JUN-30-1997             SEP-30-1997
<CASH>                                       6,659,889               7,619,588              32,741,636
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                4,211,385               4,693,756              10,248,360
<ALLOWANCES>                                 (342,774)               (342,774)               (392,774)
<INVENTORY>                                          0                       0                       0
<CURRENT-ASSETS>                            16,796,986              14,859,705              42,878,151
<PP&E>                                       6,869,820               8,584,898               9,130,697
<DEPRECIATION>                               (960,655)             (1,121,894)             (1,199,898)
<TOTAL-ASSETS>                              41,028,144              42,251,344              69,703,731
<CURRENT-LIABILITIES>                        3,118,525               2,946,960               4,453,490
<BONDS>                                              0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                        44,307                  44,345                  59,637
<OTHER-SE>                                  33,196,289              34,428,305              61,793,526
<TOTAL-LIABILITY-AND-EQUITY>                41,028,144              42,251,344              69,703,731
<SALES>                                      1,323,650               2,762,290               4,398,625
<TOTAL-REVENUES>                             6,334,551              13,675,067              22,019,230
<CGS>                                          397,729                 840,875               1,379,416
<TOTAL-COSTS>                                4,968,691              10,543,548              16,948,665
<OTHER-EXPENSES>                                     0                       0                       0
<LOSS-PROVISION>                                     0                       0                  50,000
<INTEREST-EXPENSE>                            (58,399)               (195,517)               (284,148)
<INCOME-PRETAX>                              1,424,259               3,327,036               5,354,713
<INCOME-TAX>                                   535,684               1,276,646               2,069,656
<INCOME-CONTINUING>                            888,575               2,050,390               3,285,057
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                   888,575               2,050,390               3,285,057
<EPS-PRIMARY>                                      .16                     .37                     .59
<EPS-DILUTED>                                      .16                     .36                     .57
        

</TABLE>