Frequencies for pvin_2 variable in parkwork dataset :

        vin |
character(2 |
          ) |      Freq.     Percent        Cum.
------------+-----------------------------------
            |          3        0.26        0.26
          0 |          9        0.79        1.06
          1 |          3        0.26        1.32
          6 |          1        0.09        1.41
          8 |          1        0.09        1.50
          9 |         54        4.75        6.25
          A |         27        2.38        8.63
          B |         38        3.35       11.97
          C |         41        3.61       15.58
          D |         39        3.43       19.01
          E |          7        0.62       19.63
          F |        250       22.01       41.64
          G |        206       18.13       59.77
          H |        100        8.80       68.57
          J |         29        2.55       71.13
          K |          4        0.35       71.48
          L |         16        1.41       72.89
          M |         46        4.05       76.94
          N |         92        8.10       85.04
          P |          5        0.44       85.48
          R |          1        0.09       85.56
          S |         10        0.88       86.44
          T |         91        8.01       94.45
          U |          5        0.44       94.89
          V |         30        2.64       97.54
          W |          1        0.09       97.62
          X |         19        1.67       99.30
          Y |          4        0.35       99.65
          Z |          4        0.35      100.00
------------+-----------------------------------
      Total |      1,136      100.00

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