Frequencies for first 10,000 rows of contsub5 variable in nhamcsopd1994 dataset :

 controlled |
  substance |
   code for |
 medication |
         #5 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          4        0.04        0.04
          3 |          2        0.02        0.06
          4 |         12        0.12        0.18
          6 |        378        3.78        3.96
          7 |         28        0.28        4.24
          . |      9,576       95.76      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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