Frequencies for first 10,000 rows of comstat2 variable in namcs2009 dataset :

composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      4,844       48.44       48.44
  combination drug |        689        6.89       55.33
      undetermined |         94        0.94       56.27
                 . |      4,373       43.73      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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