Frequencies for first 10,000 rows of contsub4 variable in nhamcsed1992 dataset :

 Controlled |
  substance |
   code for |
    drug #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         16        0.16        0.16
          3 |          7        0.07        0.23
          4 |         17        0.17        0.40
          5 |          2        0.02        0.42
          6 |        450        4.50        4.92
          7 |         31        0.31        5.23
          . |      9,477       94.77      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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