Frequencies for first 10,000 rows of comstat3 variable in nhamcsed2011 dataset :

Composition status |
          code for |
     medication #3 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      2,548       25.48       25.48
  Combination drug |        420        4.20       29.68
      Undetermined |         27        0.27       29.95
                 . |      7,005       70.05      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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