Frequencies for first 10,000 rows of blodpres variable in namcs2004 dataset :

      blood |
   pressure |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      5,871       58.71       58.71
          1 |      4,129       41.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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