Frequencies for first 10,000 rows of blodpres variable in nhamcsed2000 dataset :

      blood |
   pressure |
       test |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      2,058       20.58       20.58
          1 |      7,942       79.42      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016