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

  HAZARDOUS |
MATERIAL-ID |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,985       99.85       99.85
       1001 |          1        0.01       99.86
       1075 |          2        0.02       99.88
       1203 |          1        0.01       99.89
       1789 |          1        0.01       99.90
       1999 |          1        0.01       99.91
       2448 |          1        0.01       99.92
       3264 |          1        0.01       99.93
       8888 |          7        0.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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