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

  hazardous |
  materials |
involvement |
  /placard- |
        hm3 |
identificat |
 ion number |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,979       99.79       99.79
       1005 |          1        0.01       99.80
       1075 |          1        0.01       99.81
       1202 |          1        0.01       99.82
       1203 |          7        0.07       99.89
       1263 |          1        0.01       99.90
       1267 |          1        0.01       99.91
       1863 |          1        0.01       99.92
       1939 |          1        0.01       99.93
       1993 |          3        0.03       99.96
       2187 |          1        0.01       99.97
       3375 |          1        0.01       99.98
       8888 |          1        0.01       99.99
       9999 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Oct 2016