Frequencies for first 10,000 rows of contsub6 variable in namcs2000 dataset :

 controlled |
  substance |
   code for |
 medication |
         #6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          1        0.01        0.01
          3 |          7        0.07        0.08
          4 |         27        0.27        0.35
          5 |          2        0.02        0.37
          6 |        368        3.68        4.05
          7 |         15        0.15        4.20
          . |      9,580       95.80      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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