Frequencies for first 10,000 rows of abruptio variable in natlterr2002 dataset :

   Abruptio |
   placenta |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         34        0.34        0.34
          2 |      9,944       99.44       99.78
          8 |         14        0.14       99.92
          9 |          8        0.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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