Frequencies for first 10,000 rows of mammo variable in namcs1998 dataset :

mammography |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,817       98.17       98.17
          1 |        183        1.83      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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