Frequencies for first 10,000 rows of comstat3 variable in nhamcsopd2007 dataset :

          for rx3, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      2,991       29.91       29.91
  combination drug |        362        3.62       33.53
                 . |      6,647       66.47      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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