Frequencies for first 10,000 rows of f_rf_ppo variable in natl2013 dataset :

       Poor |
  Pregnancy |
   Outcomes |
(rf_ppoutc) |
          R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |          2        0.02        0.02
          1 |      9,998       99.98      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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