Frequencies for first 10,000 rows of extrxray variable in nhamcsed1995 dataset :

  extremity |
      x-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      8,913       89.13       89.13
          1 |      1,087       10.87      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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