Frequencies for first 10,000 rows of f_ld_chorio variable in natlterr2013 dataset :

Chorioamnio |
      nitis |
(ld_chor) R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      1,424       14.24       14.24
          1 |      8,576       85.76      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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