Frequencies for first 10,000 rows of comstat4 variable in nhamcsopd2010 dataset :

composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
single entity drug |      2,605       26.05       26.05
  combination drug |        260        2.60       28.65
      undetermined |         37        0.37       29.02
                 . |      7,098       70.98      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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