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

  HAZARDOUS |
   MATERIAL |
INVOLVEMENT |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      9,985       99.85       99.85
          2 |         15        0.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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