Frequencies for first 10,000 rows of ca_downs variable in natl2016 dataset :

       Down |
 Syndrome C |
  Confirmed |      Freq.     Percent        Cum.
------------+-----------------------------------
          C |          3        0.03        0.03
          N |      9,987       99.87       99.90
          P |         10        0.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 4 Oct 2017