Frequencies for first 10,000 rows of comstat4 variable in nhamcsed2014 dataset :

Composition status |
          code for |
     medication #4 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      1,800       18.00       18.00
  Combination drug |        295        2.95       20.95
      Undetermined |         19        0.19       21.14
                 . |      7,886       78.86      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 11 Apr 2017