Frequencies for first 10,000 rows of op_ruptr variable in natlterr2007 dataset :

  Premature |
 Rupture of |
   Membrane |
        RFP |
605=f_ol_ru |
    pture R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      6,163       61.63       61.63
          N |      3,779       37.79       99.42
          U |          1        0.01       99.43
          Y |         57        0.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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