Frequencies for first 10,000 rows of contsub4 variable in nhamcsopd1997 dataset :

 controlled |
  substance |
   code for |
 medication |
         #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         13        0.13        0.13
          3 |          6        0.06        0.19
          4 |         39        0.39        0.58
          5 |          1        0.01        0.59
          6 |        974        9.74       10.33
          7 |         23        0.23       10.56
          . |      8,944       89.44      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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