Frequencies for first 10,000 rows of contsub2 variable in nhamcsopd2002 dataset :

 controlled |
  substance |
   code for |
 medication |
         #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         54        0.54        0.54
          3 |         37        0.37        0.91
          4 |        110        1.10        2.01
          5 |          8        0.08        2.09
          6 |      2,966       29.66       31.75
          7 |        115        1.15       32.90
          . |      6,710       67.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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