Frequencies for first 10,000 rows of comstat4 variable in nhamcsopd2009 dataset :

          for rx4, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      2,493       24.93       24.93
  combination drug |        218        2.18       27.11
      undetermined |         31        0.31       27.42
                 . |      7,258       72.58      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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