Frequencies for a9 variable in midrvacc dataset :

         a9 |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        283       60.99       60.99
          1 |          1        0.22       61.21
          2 |          5        1.08       62.28
          3 |          3        0.65       62.93
          4 |          5        1.08       64.01
          5 |          3        0.65       64.66
          6 |          6        1.29       65.95
          7 |          5        1.08       67.03
          8 |          5        1.08       68.10
          9 |          6        1.29       69.40
         10 |         11        2.37       71.77
         11 |          7        1.51       73.28
         12 |          7        1.51       74.78
         13 |          3        0.65       75.43
         14 |          8        1.72       77.16
         15 |         13        2.80       79.96
         16 |          8        1.72       81.68
         17 |          9        1.94       83.62
         18 |          2        0.43       84.05
         19 |         11        2.37       86.42
         20 |         10        2.16       88.58
         21 |          4        0.86       89.44
         22 |          8        1.72       91.16
         23 |          5        1.08       92.24
         24 |          3        0.65       92.89
         25 |          5        1.08       93.97
         26 |          3        0.65       94.61
         27 |          4        0.86       95.47
         28 |          9        1.94       97.41
         29 |          3        0.65       98.06
         30 |          2        0.43       98.49
         31 |          2        0.43       98.92
         32 |          1        0.22       99.14
         34 |          1        0.22       99.35
         36 |          1        0.22       99.57
         39 |          1        0.22       99.78
         44 |          1        0.22      100.00
------------+-----------------------------------
      Total |        464      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016