Frequencies for first 10,000 rows of shipno variable in mort1975 dataset :

     shipno |      Freq.     Percent        Cum.
------------+-----------------------------------
         01 |        927        9.27        9.27
         02 |      1,040       10.40       19.67
         03 |        930        9.30       28.97
         04 |        864        8.64       37.61
         05 |        789        7.89       45.50
         06 |        782        7.82       53.32
         07 |        778        7.78       61.10
         08 |        830        8.30       69.40
         09 |        749        7.49       76.89
         10 |        701        7.01       83.90
         11 |        693        6.93       90.83
         12 |        665        6.65       97.48
         13 |        223        2.23       99.71
         14 |         17        0.17       99.88
         15 |         10        0.10       99.98
         99 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015