Frequencies for first 10,000 rows of phyper variable in natl1998 dataset :

Hypertensio |
        n - |
  pregnancy |
 associated |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        497        4.97        4.97
          2 |      9,503       95.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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