Frequencies for first 10,000 rows of contsub4 variable in nhamcsed1993 dataset :

 controlled |
  substance |
   code for |
    drug #4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |         25        0.25        0.25
          3 |         17        0.17        0.42
          4 |         28        0.28        0.70
          5 |          2        0.02        0.72
          6 |        654        6.54        7.26
          7 |         36        0.36        7.62
          . |      9,238       92.38      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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