Frequencies for first 10,000 rows of ld_chor variable in natlterr2007 dataset :

Chorioamnio |
  nitis RFP |
613=f_ld_ch |
     orio R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      6,163       61.63       61.63
          N |      3,831       38.31       99.94
          U |          1        0.01       99.95
          Y |          5        0.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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