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

mri - other |
  than head |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,966       99.66       99.66
        yes |         34        0.34      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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