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

     Driver |
   Presence |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      9,865       98.65       98.65
          2 |         75        0.75       99.40
          3 |         57        0.57       99.97
          9 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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