Frequencies for first 10,000 rows of ctnhead variable in nhamcsed2009 dataset :

  ct scan - |
 other than |
       head |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,226       92.26       92.26
          1 |        774        7.74      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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