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

  hazardous |
  materials |
involvement |
/placard-hm |
  2 placard |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,979       99.79       99.79
          1 |          1        0.01       99.80
          2 |         20        0.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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