Frequencies for first 10,000 rows of contsub6 variable in nhamcsed1996 dataset :

 controlled |
  substance |
   code for |
    drug #6 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |          5        0.05        0.05
          3 |          7        0.07        0.12
          4 |         14        0.14        0.26
          6 |        221        2.21        2.47
          7 |         15        0.15        2.62
          . |      9,738       97.38      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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