Frequencies for first 10,000 rows of mammo variable in nhamcsopd2011 dataset :

Mammography |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,819       98.19       98.19
        Yes |        181        1.81      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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