Frequencies for prev_acc variable in vehicle dataset :

   PREVIOUS |
  ACCIDENTS |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        708       92.67       92.67
          1 |          1        0.13       92.80
         99 |         53        6.94       99.74
          . |          2        0.26      100.00
------------+-----------------------------------
      Total |        764      100.00

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