Frequencies for first 10,000 rows of cthead variable in nhamcsed2007 dataset :

  ct scan - |
       head |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,307       93.07       93.07
        yes |        693        6.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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