Frequencies for first 10,000 rows of rupture variable in natlterr2000 dataset :

  Premature |
 rupture of |
   membrane |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        216        2.16        2.16
          2 |      9,780       97.80       99.96
          9 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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