Frequencies for first 10,000 rows of comstat21 variable in nhamcsed2014 dataset :

Composition status |
          code for |
    medication #21 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |         16        0.16        0.16
  Combination drug |          2        0.02        0.18
      Undetermined |          1        0.01        0.19
                 . |      9,981       99.81      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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