Frequencies for first 10,000 rows of comstat2 variable in nhamcsed2010 dataset :

Composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      4,589       45.89       45.89
  combination drug |        828        8.28       54.17
      undetermined |         41        0.41       54.58
                 . |      4,542       45.42      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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