Frequencies for first 10,000 rows of contsub3 variable in nhamcsopd2002 dataset :

 controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         50        0.50        0.50
          3 |         12        0.12        0.62
          4 |         83        0.83        1.45
          5 |          1        0.01        1.46
          6 |      1,858       18.58       20.04
          7 |         67        0.67       20.71
          . |      7,929       79.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016