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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,187       91.87       91.87
          1 |        292        2.92       94.79
          2 |         54        0.54       95.33
          3 |         14        0.14       95.47
          4 |          2        0.02       95.49
         99 |        399        3.99       99.48
          . |         52        0.52      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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