Frequencies for first 10,000 rows of retappt variable in namcs2004 dataset :

  return at |
  specified |
       time |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      3,302       33.02       33.02
          1 |      6,698       66.98      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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