Frequencies for first 10,000 rows of ca_omph variable in natlterr2009 dataset :

Omphalocele |
        RFP |
639=f_ca_om |
      pha R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      2,449       24.49       24.49
          N |      7,548       75.48       99.97
          U |          2        0.02       99.99
          Y |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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