Frequencies for first 10,000 rows of uld_abrup variable in natlterr2005 dataset :

   Abruptio |
 placenta U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          9        0.09        0.09
          2 |      4,481       44.81       44.90
          9 |      1,765       17.65       62.55
          . |      3,745       37.45      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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