Frequencies for haz_plac variable in vehicle dataset :

  HAZARDOUS |
MATERIAL-PL |
      ACARD |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        472      100.00      100.00
------------+-----------------------------------
      Total |        472      100.00

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