Frequencies for first 10,000 rows of contsub6 variable in nhamcsopd1998 dataset :

 controlled |
  substance |
   code for |
 medication |
         #6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          1        0.01        0.01
          3 |          4        0.04        0.05
          4 |         13        0.13        0.18
          5 |          1        0.01        0.19
          6 |        364        3.64        3.83
          7 |         12        0.12        3.95
          . |      9,605       96.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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