Frequencies for first 10,000 rows of ddimer variable in nhamcsed2012 dataset :

    D-dimer |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,692       96.92       96.92
        Yes |        308        3.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 7 Nov 2016