<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   YEAR                   YEAR                   YEAR
<FISCAL-YEAR-END>                          SEP-30-1997             SEP-30-1996             SEP-30-1995
<PERIOD-END>                               SEP-30-1997             SEP-30-1996             SEP-30-1995
<CASH>                                          14,355                  21,394                  17,886
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                  245,127                 209,745                 168,469
<ALLOWANCES>                                    33,138                  17,405                  16,500
<INVENTORY>                                     21,237                  16,582                  13,264
<CURRENT-ASSETS>                               287,229                 269,439                 226,852
<PP&E>                                         512,500                 476,051                 463,186
<DEPRECIATION>                                 210,117                 186,333                 169,815
<TOTAL-ASSETS>                                 874,367                 809,612                 730,708
<CURRENT-LIABILITIES>                          185,125                 168,348                 192,221
<BONDS>                                        252,763                 262,702                 181,929
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                           608                     608                     608
<OTHER-SE>                                     374,675                 328,707                 302,988
<TOTAL-LIABILITY-AND-EQUITY>                   874,367                 809,612                 730,708
<SALES>                                      1,140,288               1,114,491                 893,869
<TOTAL-REVENUES>                             1,140,288               1,114,491                 893,869
<CGS>                                                0                       0                       0
<TOTAL-COSTS>                                1,045,180               1,024,935                 836,864
<OTHER-EXPENSES>                                     0                       0                       0
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                              16,852                  12,461                  10,817
<INCOME-PRETAX>                                 78,256                  77,095                  46,188
<INCOME-TAX>                                    33,604                  33,759                  21,750
<INCOME-CONTINUING>                             43,917                  43,180                  24,234
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                         0                       0                       0
<EPS-PRIMARY>                                     0.75                    0.72                    0.43<F1>
<EPS-DILUTED>                                     0.73                    0.71                    0.42
<FN>
<F1>EPS-Primary reflects EPS-Basic
</FN>
        

</TABLE>