Frequencies for first 10,000 rows of doa variable in nhamcsed2007 dataset :

        doa |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,996       99.96       99.96
        yes |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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