Frequencies for first 10,000 rows of phyper variable in linkco1991us_num dataset :

Hypertensio |
        n - |
pregnancy-a |
  ssociated |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        205        2.05        2.05
          2 |      9,515       95.15       97.20
          9 |        280        2.80      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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