Frequencies for first 10,000 rows of uld_prepla variable in linkpe2009psden dataset :

   Placenta |
   previa U |
(f_uld_prep |
   lace rep |
      flag) |      Freq.     Percent        Cum.
------------+-----------------------------------
          . |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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