Frequencies for first 10,000 rows of comstat3 variable in nhamcsed2012 dataset :

Composition status |
          code for |
     medication #3 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      2,631       26.31       26.31
  Combination drug |        438        4.38       30.69
      Undetermined |         40        0.40       31.09
                 . |      6,891       68.91      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 7 Nov 2016