Frequencies for first 10,000 rows of ddimer variable in nhamcsed2015 dataset :

    D-dimer |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,764       97.64       97.64
        Yes |        236        2.36      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Nov 2017