Frequencies for first 10,000 rows of comstat4 variable in nhamcsed2010 dataset :

Composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      1,609       16.09       16.09
  combination drug |        301        3.01       19.10
      undetermined |         15        0.15       19.25
                 . |      8,075       80.75      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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