Frequencies for first 10,000 rows of comstat2 variable in nhamcsopd2010 dataset :

composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      4,508       45.08       45.08
  combination drug |        579        5.79       50.87
      undetermined |        110        1.10       51.97
                 . |      4,803       48.03      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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