Frequencies for first 10,000 rows of ca_anen variable in natlterr2008 dataset :

Anencephaly |
        RFP |
635=f_ca_an |
       en R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      6,061       60.61       60.61
          N |      3,939       39.39      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 May 2016