Frequencies for first 10,000 rows of op_ecvf variable in natlterr2010 dataset :

     Failed |
   External |
   Cephalic |
Version RFP |
604=f_ob_fa |
       il R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      4,656       46.56       46.56
          N |      4,324       43.24       89.80
          U |      1,010       10.10       99.90
          Y |         10        0.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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