Frequencies for pvin_4 variable in parkwork dataset :

        vin |
character(4 |
          ) |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         13        1.13        1.13
          1 |          2        0.17        1.31
          2 |          4        0.35        1.66
          3 |          3        0.26        1.92
          4 |          3        0.26        2.18
          5 |          8        0.70        2.88
          6 |          2        0.17        3.05
          7 |          3        0.26        3.32
          9 |         53        4.62        7.94
          A |         66        5.76       13.70
          B |         71        6.20       19.90
          C |         96        8.38       28.27
          D |         72        6.28       34.55
          E |        105        9.16       43.72
          F |         91        7.94       51.66
          G |         50        4.36       56.02
          H |         85        7.42       63.44
          J |         55        4.80       68.24
          K |         30        2.62       70.86
          L |         21        1.83       72.69
          M |         21        1.83       74.52
          N |         38        3.32       77.84
          P |         19        1.66       79.49
          R |         44        3.84       83.33
          S |         32        2.79       86.13
          T |         13        1.13       87.26
          U |          8        0.70       87.96
          V |         10        0.87       88.83
          W |         49        4.28       93.11
          X |          8        0.70       93.80
          Y |         33        2.88       96.68
          Z |         38        3.32      100.00
------------+-----------------------------------
      Total |      1,146      100.00

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