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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,046       90.46       90.46
          1 |        256        2.56       93.02
          2 |         29        0.29       93.31
          3 |          5        0.05       93.36
          4 |          3        0.03       93.39
          5 |          2        0.02       93.41
         99 |        599        5.99       99.40
          . |         60        0.60      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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