Frequencies for first 10,000 rows of mammo variable in nhamcsopd2002 dataset :

  mammogram |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,809       98.09       98.09
          1 |        191        1.91      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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