Frequencies for first 10,000 rows of contsub4 variable in namcs1999 dataset :

 controlled |
  substance |
   code for |
 medication |
         #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          7        0.07        0.07
          3 |         13        0.13        0.20
          4 |         51        0.51        0.71
          6 |      1,028       10.28       10.99
          7 |         29        0.29       11.28
          . |      8,872       88.72      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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