Frequencies for first 10,000 rows of urf_phyper variable in natl2009 dataset :

  Pregnancy |
 Associated |
Hypertensio |
      n RFP |
689=f_urf_p |
  hyper U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        522        5.22        5.22
          2 |      9,467       94.67       99.89
          9 |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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