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

  hazardous |
  materials |
involvement |
/placard-hm |
          1 |
-involvemen |
          t |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      9,981       99.81       99.81
          2 |         19        0.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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