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

  HAZARDOUS |
MATERIAL-ID |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,975       99.75       99.75
       1013 |          1        0.01       99.76
       1075 |          2        0.02       99.78
       1203 |         11        0.11       99.89
       1267 |          3        0.03       99.92
       1444 |          1        0.01       99.93
       1993 |          1        0.01       99.94
       2051 |          1        0.01       99.95
       3082 |          1        0.01       99.96
       3262 |          1        0.01       99.97
       8888 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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