Frequencies for first 10,000 rows of comstat2 variable in nhamcsopd2008 dataset :

          for rx2, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      4,431       44.31       44.31
  combination drug |        544        5.44       49.75
      undetermined |          1        0.01       49.76
                 . |      5,024       50.24      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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