Frequencies for first 10,000 rows of contsub6 variable in nhamcsopd2002 dataset :

 controlled |
  substance |
   code for |
 medication |
         #6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         12        0.12        0.12
          3 |          3        0.03        0.15
          4 |         25        0.25        0.40
          6 |        519        5.19        5.59
          7 |         19        0.19        5.78
          . |      9,422       94.22      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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