Frequencies for first 10,000 rows of comstat1 variable in nhamcsed2011 dataset :

Composition status |
          code for |
     medication #1 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      6,603       66.03       66.03
  Combination drug |      1,215       12.15       78.18
      Undetermined |         52        0.52       78.70
                 . |      2,130       21.30      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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