Frequencies for first 10,000 rows of rupture variable in natlterr1996 dataset :

  Premature |
 rupture of |
   membrane |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        158        1.58        1.58
          2 |      9,831       98.31       99.89
          9 |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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