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

   psa test |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,943       99.43       99.43
        yes |         57        0.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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