Frequencies for haz_cno variable in vehicle dataset :

  HAZARDOUS |
MATERIAL-CL |
     ASS NO |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        543       99.82       99.82
         88 |          1        0.18      100.00
------------+-----------------------------------
      Total |        544      100.00

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