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

    Vehicle |
       Role |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        299        2.99        2.99
          1 |      7,297       72.97       75.96
          2 |      2,077       20.77       96.73
          3 |        299        2.99       99.72
          9 |         28        0.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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