Frequencies for first 10,000 rows of phyper variable in natl1992 dataset :

Hypertensio |
        n - |
  pregnancy |
 associated |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        307        3.07        3.07
          2 |      9,667       96.67       99.74
          9 |         26        0.26      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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