Frequencies for a_imp2 variable in veh_aux dataset :

  Principal |
     Impact |
      Point |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         35        4.87        4.87
          2 |        497       69.22       74.09
          3 |         60        8.36       82.45
          4 |         47        6.55       89.00
          5 |         61        8.50       97.49
          6 |         18        2.51      100.00
------------+-----------------------------------
      Total |        718      100.00

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