Frequencies for first 10,000 rows of contsub4 variable in nhamcsopd1992 dataset :

 Controlled |
  substance |
   code for |
 medication |
         #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          7        0.07        0.07
          3 |         14        0.14        0.21
          4 |         37        0.37        0.58
          5 |          1        0.01        0.59
          6 |        676        6.76        7.35
          7 |         62        0.62        7.97
          . |      9,203       92.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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