Frequencies for a4 variable in midrvacc dataset :

         a4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        279       60.13       60.13
          1 |          1        0.22       60.34
          2 |          6        1.29       61.64
          3 |          5        1.08       62.72
          4 |          4        0.86       63.58
          5 |          2        0.43       64.01
          6 |          1        0.22       64.22
          7 |          3        0.65       64.87
          8 |          9        1.94       66.81
          9 |         10        2.16       68.97
         10 |          6        1.29       70.26
         11 |          8        1.72       71.98
         12 |         11        2.37       74.35
         13 |          7        1.51       75.86
         14 |          9        1.94       77.80
         15 |         13        2.80       80.60
         16 |          8        1.72       82.33
         17 |          7        1.51       83.84
         18 |          3        0.65       84.48
         19 |         14        3.02       87.50
         20 |          8        1.72       89.22
         21 |          4        0.86       90.09
         22 |          7        1.51       91.59
         23 |          4        0.86       92.46
         24 |          3        0.65       93.10
         25 |          6        1.29       94.40
         26 |          2        0.43       94.83
         27 |          4        0.86       95.69
         28 |          8        1.72       97.41
         29 |          3        0.65       98.06
         30 |          1        0.22       98.28
         31 |          3        0.65       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
         41 |          1        0.22      100.00
------------+-----------------------------------
      Total |        464      100.00

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