Frequencies for first 10,000 rows of contsub4 variable in namcs1997 dataset :

 controlled |
  substance |
   code for |
 medication |
         #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         10        0.10        0.10
          3 |         13        0.13        0.23
          4 |         73        0.73        0.96
          5 |          5        0.05        1.01
          6 |      1,533       15.33       16.34
          7 |         25        0.25       16.59
          . |      8,341       83.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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