Frequencies for first 10,000 rows of xray variable in nhamcsed2007 dataset :

      x-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      6,451       64.51       64.51
        yes |      3,549       35.49      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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