Frequencies for first 10,000 rows of f_ca_downs variable in natl2006 dataset :

      Downs |
   Syndrome |
(ca_down) R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,991       99.91       99.91
          1 |          9        0.09      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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