Frequencies for first 10,000 rows of f_ld_chorio variable in natlterr2011 dataset :

Chorioamnio |
      nitis |
(ld_chor) R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      5,590       55.90       55.90
          1 |      4,410       44.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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