Frequencies for first 10,000 rows of comstat5 variable in nhamcsopd2011 dataset :

Composition status |
          code for |
     Medication #5 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      1,898       18.98       18.98
  Combination drug |        153        1.53       20.51
      Undetermined |         23        0.23       20.74
                 . |      7,926       79.26      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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