Frequencies for first 10,000 rows of rupture variable in natl1997 dataset :

  Premature |
 rupture of |
   membrane |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        244        2.44        2.44
          2 |      9,749       97.49       99.93
          9 |          7        0.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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