Frequencies for first 10,000 rows of urf_phyper variable in natl2004 dataset :

  Pregnancy |
 Associated |
Hypertensio |
      n U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        352        3.52        3.52
          2 |      8,667       86.67       90.19
          9 |        981        9.81      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 21 Jan 2016