Frequencies for first 10,000 rows of ca_omph variable in natl2013 dataset :

Omphalocele |
        RFP |
639=f_ca_om |
      pha R |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,998       99.98       99.98
          Y |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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