Frequencies for first 10,000 rows of comstat1 variable in nhamcsed2005 dataset :

composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      6,281       62.81       62.81
  combination drug |      1,315       13.15       75.96
      undetermined |        140        1.40       77.36
                 . |      2,264       22.64      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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