Frequencies for first 10,000 rows of contsub5 variable in nhamcsopd1993 dataset :

 controlled |
  substance |
   code for |
 medication |
         #5 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         18        0.18        0.18
          3 |          8        0.08        0.26
          4 |         25        0.25        0.51
          5 |          2        0.02        0.53
          6 |        446        4.46        4.99
          7 |         39        0.39        5.38
          . |      9,462       94.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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