Frequencies for first 10,000 rows of extrxray variable in nhamcsed2002 dataset :

  extremity |
      x-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,119       91.19       91.19
          1 |        881        8.81      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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