Frequencies for first 10,000 rows of exp_dt variable in drug2013q4 dataset :

 Expiration |
date of the |
drug.Multip |
   le dates |
  possible. |      Freq.     Percent        Cum.
------------+-----------------------------------
  31jan2008 |          1        0.01        0.01
  30apr2009 |          1        0.01        0.02
  30sep2009 |          1        0.01        0.03
  28feb2010 |          1        0.01        0.04
  30apr2010 |          1        0.01        0.05
  03jun2011 |          1        0.01        0.06
  30jun2012 |          1        0.01        0.07
          . |      9,993       99.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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