Frequencies for first 10,000 rows of xray variable in nhamcsed2014 dataset :

      X-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      6,857       68.57       68.57
        Yes |      3,143       31.43      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 11 Apr 2017