Frequencies for tra_cont variable in accident dataset :

    TRAFFIC |
   CONTROLS |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        360       93.75       93.75
         20 |         24        6.25      100.00
------------+-----------------------------------
      Total |        384      100.00

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