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

     DRIVER |
   PRESENCE |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      9,817       98.17       98.17
          2 |         80        0.80       98.97
          3 |        102        1.02       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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