Frequencies for impacts variable in vehnit dataset :

    VEHICLE |
       ROLE |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |          4        0.31        0.31
          1 |         11        0.86        1.18
          2 |      1,170       91.98       93.16
          3 |         86        6.76       99.92
          9 |          1        0.08      100.00
------------+-----------------------------------
      Total |      1,272      100.00

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