Frequencies for first 10,000 rows of contsub6 variable in nhamcsopd2000 dataset :

 controlled |
  substance |
   code for |
 medication |
         #6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          8        0.08        0.08
          3 |          4        0.04        0.12
          4 |         26        0.26        0.38
          5 |          1        0.01        0.39
          6 |        490        4.90        5.29
          7 |         66        0.66        5.95
          . |      9,405       94.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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