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

     Driver |
   Training |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         76        0.76        0.76
          1 |         34        0.34        1.10
          2 |          3        0.03        1.13
          3 |          4        0.04        1.17
          4 |          6        0.06        1.23
          6 |         17        0.17        1.40
          9 |      9,860       98.60      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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