Frequencies for first 10,000 rows of uld_abrup variable in natlterr2003 dataset :

   Abruptio |
 placenta U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         33        0.33        0.33
          2 |      9,941       99.41       99.74
          8 |         23        0.23       99.97
          9 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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