Frequencies for first 10,000 rows of contsub2 variable in nhamcsed1993 dataset :

 controlled |
  substance |
   code for |
    drug #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         96        0.96        0.96
          3 |         99        0.99        1.95
          4 |         76        0.76        2.71
          5 |         26        0.26        2.97
          6 |      3,141       31.41       34.38
          7 |        178        1.78       36.16
          . |      6,384       63.84      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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