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

  Prolonged |
  Labor RFP |
607=f_ol_pr |
    olong R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      2,536       25.36       25.36
          N |      6,303       63.03       88.39
          U |      1,126       11.26       99.65
          Y |         35        0.35      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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