Frequencies for first 10,000 rows of comstat3 variable in nhamcsopd2003 dataset :

composition status |
          code for |
     medication #3 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      2,235       22.35       22.35
  combination drug |        226        2.26       24.61
      undetermined |         59        0.59       25.20
                 . |      7,480       74.80      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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