Frequencies for first 10,000 rows of mammo variable in nhamcsopd2009 dataset :

mammography |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,889       98.89       98.89
        yes |        111        1.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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