Frequencies for first 10,000 rows of contsub3 variable in nhamcsopd2000 dataset :

 controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         34        0.34        0.34
          3 |         22        0.22        0.56
          4 |         71        0.71        1.27
          5 |          5        0.05        1.32
          6 |      1,949       19.49       20.81
          7 |         62        0.62       21.43
          . |      7,857       78.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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