Frequencies for first 10,000 rows of contsub3 variable in nhamcsopd1992 dataset :

 Controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         15        0.15        0.15
          3 |         15        0.15        0.30
          4 |         42        0.42        0.72
          5 |          5        0.05        0.77
          6 |      1,262       12.62       13.39
          7 |        106        1.06       14.45
          . |      8,555       85.55      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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