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

  HAZARDOUS |
      CARGO |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,873       98.73       98.73
          1 |         22        0.22       98.95
          2 |          2        0.02       98.97
          3 |         13        0.13       99.10
          9 |         90        0.90      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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