Frequencies for first 10,000 rows of chestxry variable in nhamcsed1994 dataset :

chest x-ray |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      8,353       83.53       83.53
          1 |      1,647       16.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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