Frequencies for first 10,000 rows of retappt variable in namcs1996 dataset :

  return at |
  specified |
       time |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      3,180       31.80       31.80
          1 |      6,820       68.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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