Frequencies for first 10,000 rows of contsub3 variable in namcs1994 dataset :

 controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          5        0.05        0.05
          3 |         46        0.46        0.51
          4 |        102        1.02        1.53
          5 |         23        0.23        1.76
          6 |      1,989       19.89       21.65
          7 |         79        0.79       22.44
          . |      7,756       77.56      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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