Frequencies for first 10,000 rows of extrxray variable in nhamcsed2003 dataset :

  extremity |
      x-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      8,914       89.14       89.14
        yes |      1,086       10.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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