Frequencies for first 10,000 rows of xray variable in nhamcsed2015 dataset :

      X-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      6,731       67.31       67.31
        Yes |      3,269       32.69      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Nov 2017