Frequencies for impacts variable in vehicle dataset :

    VEHICLE |
       ROLE |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         14        2.97        2.97
          1 |        330       69.92       72.88
          2 |        109       23.09       95.97
          3 |         19        4.03      100.00
------------+-----------------------------------
      Total |        472      100.00

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