Frequencies for first 10,000 rows of contsub4 variable in nhamcsed2001 dataset :

 controlled |
  substance |
   code for |
    drug #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         44        0.44        0.44
          3 |         35        0.35        0.79
          4 |         38        0.38        1.17
          6 |        919        9.19       10.36
          7 |         62        0.62       10.98
          . |      8,902       89.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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