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

Prepregnanc |
          y |
Hypertensio |
      n RFP |
584=f_rf_ph |
     yper R |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,571       95.71       95.71
          U |        167        1.67       97.38
          Y |        262        2.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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