Frequencies for first 10,000 rows of contsub2 variable in nhamcsed1997 dataset :

 controlled |
  substance |
   code for |
    drug #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        134        1.34        1.34
          3 |        161        1.61        2.95
          4 |        127        1.27        4.22
          5 |         16        0.16        4.38
          6 |      3,399       33.99       38.37
          7 |        135        1.35       39.72
          . |      6,028       60.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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