Frequencies for first 10,000 rows of comstat1 variable in nhamcsopd2005 dataset :

composition status |
   code for med #1 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      5,224       52.24       52.24
  combination drug |      1,263       12.63       64.87
      undetermined |        217        2.17       67.04
                 . |      3,296       32.96      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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