Frequencies for first 10,000 rows of uca_downs variable in natl2014 dataset :

       Down |
 Syndrome 1 |
    Anomaly |
   reported |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          3        0.03        0.03
          2 |      9,997       99.97      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Jun 2016