Frequencies for first 10,000 rows of comstat2 variable in namcs2012 dataset :

Composition status |
          code for |
      medication 2 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      4,162       41.62       41.62
  Combination drug |        508        5.08       46.70
      Undetermined |        184        1.84       48.54
                 . |      5,146       51.46      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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