Frequencies for first 10,000 rows of pt variable in namcs2008 dataset :

   physical |
    therapy |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,819       98.19       98.19
        yes |        181        1.81      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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