Frequencies for first 10,000 rows of ca_omph variable in natlterr2007 dataset :

Omphalocele |
        RFP |
639=f_ca_om |
      pha R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      6,163       61.63       61.63
          N |      3,832       38.32       99.95
          U |          1        0.01       99.96
          Y |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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