Frequencies for first 10,000 rows of rupture variable in natl1989 dataset :

  Premature |
 rupture of |
   membrane |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        306        3.06        3.06
          2 |      9,469       94.69       97.75
          9 |        225        2.25      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016