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

  HAZARDOUS |
      CARGO |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,877       98.77       98.77
          1 |         29        0.29       99.06
          2 |          1        0.01       99.07
          3 |          2        0.02       99.09
          9 |         91        0.91      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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