Frequencies for first 10,000 rows of contsub6 variable in nhamcsopd1999 dataset :

 controlled |
  substance |
   code for |
 medication |
         #6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         17        0.17        0.17
          3 |          2        0.02        0.19
          4 |         20        0.20        0.39
          5 |          1        0.01        0.40
          6 |        398        3.98        4.38
          7 |          8        0.08        4.46
          . |      9,554       95.54      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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