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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,170       91.70       91.70
          1 |        295        2.95       94.65
          2 |         52        0.52       95.17
          3 |          5        0.05       95.22
          4 |          2        0.02       95.24
         99 |        414        4.14       99.38
          . |         62        0.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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