Frequencies for first 10,000 rows of downs variable in natl1992 dataset :

     Down's |
   syndrome |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          7        0.07        0.07
          2 |      9,990       99.90       99.97
          9 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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