Frequencies for first 10,000 rows of comstat2 variable in nhamcsopd2007 dataset :

          for rx2, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      4,135       41.35       41.35
  combination drug |        538        5.38       46.73
                 . |      5,327       53.27      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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