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

 return prn |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      7,898       78.98       78.98
        yes |      2,102       21.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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