Frequencies for first 10,000 rows of xray variable in namcs1996 dataset :

      x-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,304       93.04       93.04
          1 |        696        6.96      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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