Frequencies for first 10,000 rows of comstat2 variable in nhamcsed2004 dataset :

composition status |
          code for |
     medication #2 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      4,207       42.07       42.07
  combination drug |        779        7.79       49.86
      undetermined |        108        1.08       50.94
                 . |      4,906       49.06      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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