Frequencies for first 10,000 rows of extrxray variable in nhamcsed1992 dataset :

  Extremity |
      X-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      8,441       84.41       84.41
          1 |      1,559       15.59      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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