Frequencies for first 10,000 rows of comstat4 variable in namcs2009 dataset :

composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      2,643       26.43       26.43
  combination drug |        301        3.01       29.44
      undetermined |         30        0.30       29.74
                 . |      7,026       70.26      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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