Frequencies for first 10,000 rows of ctchest variable in nhamcsed2015 dataset :

  CT scan - |
      chest |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,779       97.79       97.79
        Yes |        221        2.21      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Nov 2017