Frequencies for first 10,000 rows of contsub2 variable in nhamcsed1995 dataset :

 controlled |
  substance |
   code for |
    drug #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        138        1.38        1.38
          3 |        157        1.57        2.95
          4 |        124        1.24        4.19
          5 |         20        0.20        4.39
          6 |      3,131       31.31       35.70
          7 |        118        1.18       36.88
          . |      6,312       63.12      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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