Frequencies for first 10,000 rows of cf3 variable in accident dataset :

    RELATED |
   FACTOR 3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,888       98.88       98.88
         19 |          5        0.05       98.93
         20 |          1        0.01       98.94
         99 |        106        1.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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