Frequencies for first 10,000 rows of urf_phyper variable in natl2003 dataset :

  Pregnancy |
 Associated |
Hypertensio |
      n U;R |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        354        3.54        3.54
          2 |      8,826       88.26       91.80
          8 |          5        0.05       91.85
          9 |        815        8.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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