Frequencies for first 10,000 rows of comstat7 variable in nhamcsopd2005 dataset :

composition status |
   code for med #7 |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |        550        5.50        5.50
  combination drug |         63        0.63        6.13
      undetermined |         11        0.11        6.24
                 . |      9,376       93.76      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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