Frequencies for first 10,000 rows of prev_acc variable in vehicle dataset :

   Previous |
   Recorded |
    crashes |      Freq.     Percent        Cum.
------------+-----------------------------------
         -1 |         15        0.15        0.15
          0 |      8,142       81.42       81.57
          1 |        779        7.79       89.36
          2 |        118        1.18       90.54
          3 |         21        0.21       90.75
          4 |          3        0.03       90.78
          5 |          1        0.01       90.79
         98 |        487        4.87       95.66
         99 |        387        3.87       99.53
          . |         47        0.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016