Frequencies for first 10,000 rows of mammo variable in nhamcsopd2000 dataset :

mammography |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,825       98.25       98.25
          1 |        175        1.75      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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