<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<CURRENCY> USD

<S>                          <C>                  <C>                  <C>                   <C>                <C>
<PERIOD-TYPE>                6-MOS                3-MOS                12-MOS                9-MOS              6-MOS
<FISCAL-YEAR-END>                   DEC-31-1999          DEC-31-1999          DEC-31-1998          DEC-31-1998      DEC-31-1998
<PERIOD-START>                      JAN-01-1999          JAN-01-1999          JAN-01-1998          JAN-01-1998      JAN-01-1998
<PERIOD-END>                        JUN-30-1999          MAR-31-1999          DEC-31-1998          SEP-30-1998      JUN-30-1998
<EXCHANGE-RATE>                               1                    1                    1                    1                1
<CASH>                               34,011,617           32,551,645           50,522,744           33,640,974      151,246,159
<SECURITIES>                                  0                    0                    0                    0                0
<RECEIVABLES>                        67,518,397           57,832,747           49,073,840           39,944,931       29,716,528
<ALLOWANCES>                        (2,820,675)          (3,306,601)          (2,077,198)          (1,495,206)      (1,369,147)
<INVENTORY>                                   0                    0                    0                    0                0
<CURRENT-ASSETS>                    105,856,827           92,579,695          102,394,461           82,660,722      187,835,271
<PP&E>                              169,659,060          169,419,155          150,727,612          155,651,101        6,986,214
<DEPRECIATION>                      (6,860,974)          (5,768,748)          (2,788,615)          (9,543,791)      (1,218,576)
<TOTAL-ASSETS>                      391,104,066          372,108,957          349,646,447          325,944,531      249,563,919
<CURRENT-LIABILITIES>                25,002,729           28,660,910           28,473,153           31,145,223       19,853,419
<BONDS>                             215,005,272          196,892,128          178,893,235          167,513,935      115,000,000
<PREFERRED-MANDATORY>                         0                    0                    0                    0                0
<PREFERRED>                              71,000               71,000               73,000               73,000           73,000
<COMMON>                                901,878              901,878              900,729              883,636          883,273
<OTHER-SE>                          142,967,691          138,020,798          133,446,512          120,960,986      111,964,740
<TOTAL-LIABILITY-AND-EQUITY>        391,104,066          372,108,957          349,646,447          325,944,531      249,563,919
<SALES>                             104,297,297           50,717,834          146,918,478          103,417,296       63,812,349
<TOTAL-REVENUES>                    104,297,297           50,717,834          146,918,478          103,417,296       63,812,349
<CGS>                                         0                    0                    0                    0                0
<TOTAL-COSTS>                        65,513,072           31,569,774           92,030,009           65,773,739       40,735,799
<OTHER-EXPENSES>                     14,978,199            7,346,930           24,181,801           17,162,961       11,152,284
<LOSS-PROVISION>                        183,154              721,804              887,753              801,238          703,133
<INTEREST-EXPENSE>                    7,187,814            3,515,544            8,493,224            5,886,303        3,666,710
<INCOME-PRETAX>                      20,179,044            9,748,209           30,625,409           21,120,652       12,748,902
<INCOME-TAX>                          7,970,972            3,850,543           12,556,418            8,659,468        5,226,777
<INCOME-CONTINUING>                  12,204,722            5,895,841           18,058,941           12,452,959        7,515,725
<DISCONTINUED>                                0                    0                    0                    0                0
<EXTRAORDINARY>                               0                    0                    0                    0                0
<CHANGES>                                     0                    0                    0                    0                0
<NET-INCOME>                         12,204,722            5,895,841           18,058,941           12,452,959        7,515,725
<EPS-BASIC>                                0.68                 0.33                 1.02                 0.71             0.43
<EPS-DILUTED>                              0.66                 0.32                  .99                 0.69             0.42


</TABLE>