Frequencies for first 10,000 rows of xray variable in nhamcsed2011 dataset :

      X-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      6,561       65.61       65.61
        Yes |      3,439       34.39      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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