Frequencies for first 10,000 rows of glaucoma variable in nhamcsopd1997 dataset :

   glaucoma |
       exam |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,761       97.61       97.61
          1 |        239        2.39      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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