Frequencies for first 10,000 rows of comstat6 variable in nhamcsopd2005 dataset :

composition status |
   code for med #6 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |        775        7.75        7.75
  combination drug |         63        0.63        8.38
      undetermined |         12        0.12        8.50
                 . |      9,150       91.50      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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