Frequencies for prev_spd variable in vehicle dataset :

   PREVIOUS |
   SPEEDING |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        649       84.95       84.95
          1 |         40        5.24       90.18
          2 |         13        1.70       91.88
          3 |          6        0.79       92.67
          4 |          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