Frequencies for first 10,000 rows of f_uca_downs variable in natlterr2007 dataset :

       Down |
   Syndrome |
(ucs_downs) |
          U |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |         11        0.11        0.11
          1 |      9,989       99.89      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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