Frequencies for first 10,000 rows of abruptio variable in natl1994 dataset :

   Abruptio |
   placenta |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         47        0.47        0.47
          2 |      9,914       99.14       99.61
          9 |         39        0.39      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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