Frequencies for first 10,000 rows of ca_downs variable in natlterr2014 dataset 

       Down |
 Syndrome C |
  Confirmed |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      1,077       10.77       10.77
          C |          2        0.02       10.79
          N |      8,807       88.07       98.86
          P |          4        0.04       98.90
          U |        110        1.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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