Frequencies for first 10,000 rows of retprn variable in namcs2005 dataset :

 return prn |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      6,553       65.53       65.53
          1 |      3,447       34.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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