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

   Previous |
   Recorded |
    crashes |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      8,287       82.87       82.87
          1 |        825        8.25       91.12
          2 |         87        0.87       91.99
          3 |         14        0.14       92.13
          4 |          2        0.02       92.15
          6 |          1        0.01       92.16
         98 |        318        3.18       95.34
         99 |        405        4.05       99.39
        998 |         61        0.61      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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