Frequencies for first 10,000 rows of op_ecvf variable in natlterr2011 dataset :

     Failed |
   External |
   Cephalic |
Version RFP |
604=f_ob_fa |
       il R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      2,536       25.36       25.36
          N |      6,311       63.11       88.47
          U |      1,142       11.42       99.89
          Y |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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