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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      8,997       89.97       89.97
          1 |        288        2.88       92.85
          2 |         66        0.66       93.51
          3 |          8        0.08       93.59
          4 |          5        0.05       93.64
         99 |        571        5.71       99.35
          . |         65        0.65      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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