Frequencies for first 10,000 rows of dr_sf4 variable in vehicle dataset :

     driver |
    related |
 factors (4 |
   choices) |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,505       95.05       95.05
         36 |          1        0.01       95.06
         39 |          1        0.01       95.07
         51 |          1        0.01       95.08
         91 |          2        0.02       95.10
         99 |        490        4.90      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Oct 2016