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

  HAZARDOUS |
      CARGO |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,817       98.17       98.17
          1 |         36        0.36       98.53
          2 |          4        0.04       98.57
          3 |          2        0.02       98.59
          9 |        141        1.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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