Frequencies for ptype variable in parkwork dataset :

  unit type |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        689       60.81       60.81
          3 |        416       36.72       97.53
          4 |         28        2.47      100.00
------------+-----------------------------------
      Total |      1,133      100.00

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