Frequencies for first 10,000 rows of xray variable in namcs2011 dataset :

      X-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,405       94.05       94.05
        Yes |        595        5.95      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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