Frequencies for phaz_inv variable in parkwork dataset :

  hazardous |
  materials |
involvement |
/placard-hm |
          1 |
-involvemen |
          t |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,133      100.00      100.00
------------+-----------------------------------
      Total |      1,133      100.00

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