Frequencies for first 10,000 rows of contsub1 variable in nhamcsopd1995 dataset :

 controlled |
  substance |
   code for |
 medication |
         #1 |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |        150        1.50        1.50
          3 |         78        0.78        2.28
          4 |        117        1.17        3.45
          5 |          7        0.07        3.52
          6 |      5,327       53.27       56.79
          7 |        275        2.75       59.54
          . |      4,046       40.46      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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