Frequencies for first 10,000 rows of exp_dt variable in drug2013q1 dataset :

 Expiration |
date of the |
drug.Multip |
   le dates |
  possible. |      Freq.     Percent        Cum.
------------+-----------------------------------
  01aug2009 |          1        0.01        0.01
  31jul2012 |          1        0.01        0.02
          . |      9,998       99.98      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Apr 2017