Frequencies for impacts variable in vehicle dataset :

    VEHICLE |
       ROLE |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         33        4.32        4.32
          1 |        548       71.73       76.05
          2 |        170       22.25       98.30
          3 |         13        1.70      100.00
------------+-----------------------------------
      Total |        764      100.00

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