Frequencies for first 10,000 rows of comstat1 variable in nhamcsed2012 dataset :

Composition status |
          code for |
     medication #1 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      6,300       63.00       63.00
  Combination drug |      1,128       11.28       74.28
      Undetermined |         76        0.76       75.04
                 . |      2,496       24.96      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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