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

     driver |
   presence |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         68        0.68        0.68
          1 |      9,931       99.31       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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