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

  Premature |
 Rupture of |
   Membrane |
        RFP |
605=f_ol_ru |
    pture R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      2,536       25.36       25.36
          N |      6,255       62.55       87.91
          U |      1,126       11.26       99.17
          Y |         83        0.83      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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