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

     DRIVER |
   PRESENCE |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      9,867       98.67       98.67
          2 |         60        0.60       99.27
          3 |         73        0.73      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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