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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,188       91.88       91.88
          1 |        254        2.54       94.42
          2 |         44        0.44       94.86
          3 |          8        0.08       94.94
          4 |          2        0.02       94.96
          6 |          1        0.01       94.97
         99 |        441        4.41       99.38
          . |         62        0.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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