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

   physical |
    therapy |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,653       96.53       96.53
        yes |        347        3.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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