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

   PREVIOUS |
        DWI |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,014       90.14       90.14
          1 |        335        3.35       93.49
          2 |         78        0.78       94.27
          3 |         23        0.23       94.50
          4 |          3        0.03       94.53
         99 |        485        4.85       99.38
          . |         62        0.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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