Frequencies for first 10,000 rows of f_pwgt variable in natlterr2012 dataset :

Prepregnanc |
   y Weight |
 (pwgt_r) R |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      1,329       13.29       13.29
          1 |      8,671       86.71      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 5 May 2016