Frequencies for first 10,000 rows of echocard variable in nhamcsopd2009 dataset :

echocardiog |
        ram |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,879       98.79       98.79
        yes |        121        1.21      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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