Frequencies for first 10,000 rows of rf_ppterm variable in natlterr2014 dataset

   Previous |
    Preterm |
Birth Y Yes |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      1,077       10.77       10.77
          N |      8,751       87.51       98.28
          U |         76        0.76       99.04
          Y |         96        0.96      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 15 Jun 2016