Frequencies for first 10,000 rows of contsub2 variable in nhamcsed1998 dataset :

 controlled |
  substance |
   code for |
    drug #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        157        1.57        1.57
          3 |        125        1.25        2.82
          4 |        145        1.45        4.27
          5 |         12        0.12        4.39
          6 |      3,239       32.39       36.78
          7 |         92        0.92       37.70
          . |      6,230       62.30      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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