Frequencies for first 10,000 rows of comstat6 variable in nhamcsed2005 dataset :

composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |        307        3.07        3.07
  combination drug |         61        0.61        3.68
      undetermined |          8        0.08        3.76
                 . |      9,624       96.24      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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