Frequencies for first 10,000 rows of rf_ghyp variable in natlterr2009 dataset :

Gestational |
Hypertensio |
      n RFP |
585=f_rf_gh |
     yper R |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      2,449       24.49       24.49
          N |      7,283       72.83       97.32
          U |          2        0.02       97.34
          Y |        266        2.66      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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