<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   YEAR                   YEAR                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1996             DEC-31-1995
<PERIOD-START>                             JAN-01-1997             JAN-01-1996             JAN-01-1995
<PERIOD-END>                               DEC-31-1997             DEC-31-1996             DEC-31-1995
<CASH>                                          39,308                   6,729                       0
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                   36,411                  26,157                  13,848
<ALLOWANCES>                                   (6,912)                 (9,157)                 (6,903)
<INVENTORY>                                          0                       0                       0
<CURRENT-ASSETS>                                     0                       0                       0
<PP&E>                                       1,793,327               1,172,034                 646,976
<DEPRECIATION>                               (236,220)               (110,260)                (52,657)
<TOTAL-ASSETS>                               1,948,944               1,341,854                 841,990
<CURRENT-LIABILITIES>                                0                       0                       0
<BONDS>                                      1,107,425                 770,625                 426,781
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                    121,000                  94,000                       0
<COMMON>                                           731                     527                     453
<OTHER-SE>                                     625,963                 424,003                 379,966
<TOTAL-LIABILITY-AND-EQUITY>                 1,948,944               1,341,854                 841,990
<SALES>                                              0                       0                       0
<TOTAL-REVENUES>                               229,907                 158,526                 115,048
<CGS>                                                0                       0                       0
<TOTAL-COSTS>                                  123,092                  92,534                  65,286
<OTHER-EXPENSES>                                 2,478                   1,063                       0
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                              57,472                  40,233                  27,916
<INCOME-PRETAX>                                 46,865                  24,696                  21,846
<INCOME-TAX>                                         0                       0                       0
<INCOME-CONTINUING>                             46,865                  24,696                  21,846
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                    46,865                  24,696                  21,846
<EPS-PRIMARY>                                     0.54                    0.42                    0.48
<EPS-DILUTED>                                     0.54                    0.42                    0.48
        

</TABLE>