Frequencies for first 10,000 rows of urf_preterm variable in natlterr2006 dataset :

   Previous |
 Preterm or |
  Small for |
  Gestation |
        RFP |
693=f_urf_p |
   reterm U |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |          7        0.07        0.07
          2 |      4,789       47.89       47.96
          9 |      1,479       14.79       62.75
          . |      3,725       37.25      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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