Frequencies for first 10,000 rows of ld_chor variable in natlterr2015 dataset :

Chorioamnio |
nitis Y Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      1,078       10.78       10.78
          N |      8,801       88.01       98.79
          U |        102        1.02       99.81
          Y |         19        0.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Oct 2016