Frequencies for first 10,000 rows of comstat2 variable in nhamcsed2012 dataset :

Composition status |
          code for |
     medication #2 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      4,376       43.76       43.76
  Combination drug |        705        7.05       50.81
      Undetermined |         46        0.46       51.27
                 . |      4,873       48.73      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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