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

   psa test |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,928       99.28       99.28
        yes |         72        0.72      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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