Frequencies for first 10,000 rows of comstat1 variable in nhamcsopd2009 dataset :

          for rx1, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      5,500       55.00       55.00
  combination drug |      1,137       11.37       66.37
      undetermined |        125        1.25       67.62
                 . |      3,238       32.38      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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