Frequencies for impacts variable in vehicle dataset :

    VEHICLE |
       ROLE |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         17        2.72        2.72
          1 |        449       71.73       74.44
          2 |        150       23.96       98.40
          3 |         10        1.60      100.00
------------+-----------------------------------
      Total |        626      100.00

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