Frequencies for first 10,000 rows of rupture variable in natlterr1994 dataset :

  Premature |
 rupture of |
   membrane |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        223        2.23        2.23
          2 |      9,754       97.54       99.77
          9 |         23        0.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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