Frequencies for first 10,000 rows of uca_downs variable in natlterr2015 dataset :

       Down |
 Syndrome 1 |
    Anomaly |
   reported |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          5        0.05        0.05
          2 |      8,803       88.03       88.08
          9 |      1,192       11.92      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Oct 2016