Frequencies for first 10,000 rows of comstat3 variable in nhamcsopd2004 dataset :

composition status |
          code for |
     medication #3 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      2,351       23.51       23.51
  combination drug |        261        2.61       26.12
      undetermined |         72        0.72       26.84
                 . |      7,316       73.16      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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