Frequencies for first 10,000 rows of comstat4 variable in nhamcsopd2006 dataset :

          for rx4, |
composition status |
              code |      Freq.     Percent        Cum.
-------------------+-----------------------------------
Single entity drug |      1,825       18.25       18.25
  Combination drug |        195        1.95       20.20
                 . |      7,980       79.80      100.00
-------------------+-----------------------------------
             Total |     10,000      100.00

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