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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,203       92.03       92.03
          1 |        289        2.89       94.92
          2 |         56        0.56       95.48
          3 |          9        0.09       95.57
          4 |          2        0.02       95.59
         99 |        379        3.79       99.38
          . |         62        0.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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