Frequencies for first 10,000 rows of comstat5 variable in nhamcsopd2008 dataset :

          for rx5, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      1,873       18.73       18.73
  combination drug |        161        1.61       20.34
      undetermined |          5        0.05       20.39
                 . |      7,961       79.61      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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