Frequencies for first 10,000 rows of uld_abrup variable in natl2006 dataset :

   Abruptio |
   placenta |
        RFP |
714=f_uld_a |
  bruptio U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         30        0.30        0.30
          2 |      9,838       98.38       98.68
          9 |        132        1.32      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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