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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      8,936       89.36       89.36
          1 |        442        4.42       93.78
          2 |         94        0.94       94.72
          3 |         29        0.29       95.01
          4 |          3        0.03       95.04
          5 |          3        0.03       95.07
          6 |          2        0.02       95.09
          9 |          1        0.01       95.10
         99 |        490        4.90      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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