Frequencies for first 10,000 rows of comstat6 variable in nhamcsed2008 dataset :

          for rx6, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |        400        4.00        4.00
  combination drug |         51        0.51        4.51
      undetermined |          1        0.01        4.52
                 . |      9,548       95.48      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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