Frequencies for first 10,000 rows of buncreat variable in nhamcsed2006 dataset :

 bun (blood |
       urea |
nitrogen)/c |
  reatinine |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      8,010       80.10       80.10
        yes |      1,990       19.90      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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