Frequencies for first 10,000 rows of comstat2 variable in nhamcsopd2003 dataset :

composition status |
          code for |
     medication #2 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      3,393       33.93       33.93
  combination drug |        413        4.13       38.06
      undetermined |         87        0.87       38.93
                 . |      6,107       61.07      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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