Frequencies for first 10,000 rows of comstat5 variable in namcs2009 dataset :

composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      2,001       20.01       20.01
  combination drug |        196        1.96       21.97
      undetermined |         45        0.45       22.42
                 . |      7,758       77.58      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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