Frequencies for first 10,000 rows of comstat18 variable in nhamcsed2014 dataset :

Composition status |
          code for |
    medication #18 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |         25        0.25        0.25
  Combination drug |          4        0.04        0.29
      Undetermined |          1        0.01        0.30
                 . |      9,970       99.70      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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