Frequencies for first 10,000 rows of comstat7 variable in nhamcsopd2009 dataset :

          for rx7, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      1,158       11.58       11.58
  combination drug |        104        1.04       12.62
      undetermined |         14        0.14       12.76
                 . |      8,724       87.24      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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