Frequencies for first 10,000 rows of contsub6 variable in nhamcsed1999 dataset :

 controlled |
  substance |
   code for |
    drug #6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         17        0.17        0.17
          3 |          8        0.08        0.25
          4 |          5        0.05        0.30
          6 |        211        2.11        2.41
          7 |         18        0.18        2.59
          . |      9,741       97.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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