<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<MULTIPLIER> 1,000
       
<S>                             <C>                             <C>                    
<PERIOD-TYPE>                   6-MOS                           6-MOS                 
<FISCAL-YEAR-END>                          JUL-31-1998                     JUL-31-1997
<PERIOD-START>                             AUG-01-1997                     AUG-01-1996
<PERIOD-END>                               JAN-31-1998                     JAN-31-1997
<CASH>                                           3,661                           5,952
<SECURITIES>                                         0                             100
<RECEIVABLES>                                   38,933                          32,423
<ALLOWANCES>                                     1,983                           1,552
<INVENTORY>                                          0                           3,238
<CURRENT-ASSETS>                                55,212                          52,667
<PP&E>                                         121,564                         108,477
<DEPRECIATION>                                  35,071                          26,574
<TOTAL-ASSETS>                                 183,063                         167,008
<CURRENT-LIABILITIES>                           24,035                          19,422
<BONDS>                                         51,124                          70,246
<PREFERRED-MANDATORY>                                0                               0
<PREFERRED>                                          0                               0
<COMMON>                                           421                             420
<OTHER-SE>                                     105,367                          75,874
<TOTAL-LIABILITY-AND-EQUITY>                   183,063                         167,008
<SALES>                                         84,938                          72,495
<TOTAL-REVENUES>                                84,938                          72,495
<CGS>                                           25,149                          22,923
<TOTAL-COSTS>                                   54,554                          47,533
<OTHER-EXPENSES>                                 1,191                             875
<LOSS-PROVISION>                                     0                               0
<INTEREST-EXPENSE>                               2,192                           2,014
<INCOME-PRETAX>                                 28,097                          22,761
<INCOME-TAX>                                    11,239                           8,977
<INCOME-CONTINUING>                             16,858                          13,784
<DISCONTINUED>                                       0                          (1,085)
<EXTRAORDINARY>                                      0                               0
<CHANGES>                                            0                               0
<NET-INCOME>                                    16,858                          12,699
<EPS-PRIMARY>                                     1.01                             .82
<EPS-DILUTED>                                      .97                             .74 
        


</TABLE>