Frequencies for first 10,000 rows of comstat8 variable in nhamcsopd2009 dataset :

          for rx8, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |        866        8.66        8.66
  combination drug |         79        0.79        9.45
      undetermined |         11        0.11        9.56
                 . |      9,044       90.44      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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