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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,071       90.71       90.71
          1 |        264        2.64       93.35
          2 |         50        0.50       93.85
          3 |          9        0.09       93.94
          4 |          5        0.05       93.99
          6 |          1        0.01       94.00
         99 |        553        5.53       99.53
          . |         47        0.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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