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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,196       91.96       91.96
          1 |        296        2.96       94.92
          2 |         44        0.44       95.36
          3 |          2        0.02       95.38
          4 |          1        0.01       95.39
          5 |          1        0.01       95.40
         99 |        408        4.08       99.48
          . |         52        0.52      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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