Frequencies for first 10,000 rows of contsub3 variable in nhamcsopd1994 dataset :

 controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          7        0.07        0.07
          3 |         15        0.15        0.22
          4 |         48        0.48        0.70
          5 |          4        0.04        0.74
          6 |      1,434       14.34       15.08
          7 |         99        0.99       16.07
          . |      8,393       83.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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