Frequencies for first 10,000 rows of comstat1 variable in nhamcsopd2007 dataset :

          for rx1, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      5,466       54.66       54.66
  combination drug |      1,327       13.27       67.93
      undetermined |          2        0.02       67.95
                 . |      3,205       32.05      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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