Frequencies for first 10,000 rows of comstat1 variable in nhamcsed2013 dataset :

Composition status |
          code for |
     medication #1 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      6,498       64.98       64.98
  Combination drug |      1,084       10.84       75.82
      Undetermined |         75        0.75       76.57
                 . |      2,343       23.43      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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