Frequencies for first 10,000 rows of comstat2 variable in nhamcsopd2009 dataset :

          for rx2, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      4,287       42.87       42.87
  combination drug |        511        5.11       47.98
      undetermined |         89        0.89       48.87
                 . |      5,113       51.13      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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