Frequencies for first 10,000 rows of rupture variable in natl1995 dataset :

  Premature |
 rupture of |
   membrane |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        215        2.15        2.15
          2 |      9,754       97.54       99.69
          9 |         31        0.31      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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