Frequencies for first 10,000 rows of contsub5 variable in nhamcsopd1992 dataset :

 Controlled |
  substance |
   code for |
 medication |
         #5 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          2        0.02        0.02
          3 |          3        0.03        0.05
          4 |         16        0.16        0.21
          6 |        410        4.10        4.31
          7 |         23        0.23        4.54
          . |      9,546       95.46      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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