Frequencies for first 10,000 rows of echocard variable in nhamcsopd2007 dataset :

echocardiog |
        ram |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,885       98.85       98.85
        yes |        115        1.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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