Frequencies for pton_rat variable in parkwork dataset :

 ton rating |      Freq.     Percent        Cum.
------------+-----------------------------------
            |        834       76.44       76.44
          B |        156       14.30       90.74
          C |         50        4.58       95.33
          D |         47        4.31       99.63
          E |          3        0.27       99.91
         GN |          1        0.09      100.00
------------+-----------------------------------
      Total |      1,091      100.00

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