Frequencies for first 10,000 rows of op_prol variable in natlterr2008 dataset :

  Prolonged |
  Labor RFP |
607=f_ol_pr |
    olong R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      6,061       60.61       60.61
          N |      3,921       39.21       99.82
          U |          1        0.01       99.83
          Y |         17        0.17      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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