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

     Driver |
   Training |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         97        0.97        0.97
          1 |         34        0.34        1.31
          3 |          1        0.01        1.32
          4 |          4        0.04        1.36
          6 |          9        0.09        1.45
          9 |      9,855       98.55      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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