Frequencies for first 10,000 rows of f_ca_downs variable in natlterr2009 dataset :

      Downs |
   Syndrome |
(ca_down) R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,460       24.60       24.60
          1 |      7,540       75.40      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015