Frequencies for first 10,000 rows of contsub3 variable in nhamcsopd1993 dataset :

 controlled |
  substance |
   code for |
 medication |
         #3 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         25        0.25        0.25
          3 |         19        0.19        0.44
          4 |         66        0.66        1.10
          5 |          2        0.02        1.12
          6 |      1,448       14.48       15.60
          7 |        128        1.28       16.88
          . |      8,312       83.12      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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