Frequencies for first 10,000 rows of comstat5 variable in nhamcsopd2009 dataset :

          for rx5, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      1,982       19.82       19.82
  combination drug |        164        1.64       21.46
      undetermined |         23        0.23       21.69
                 . |      7,831       78.31      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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