Frequencies for first 10,000 rows of exp_dt_num variable in drug2009q2 dataset :

 Expiration |
date of the |
      drug. |
 (YYYYMMDD) |      Freq.     Percent        Cum.
------------+-----------------------------------
  30sep2008 |          1        0.01        0.01
  22dec2008 |          1        0.01        0.02
  31may2009 |          1        0.01        0.03
  01jul2009 |          1        0.01        0.04
  31aug2009 |          1        0.01        0.05
  07sep2009 |          1        0.01        0.06
  26jan2010 |          2        0.02        0.08
  29jan2010 |          1        0.01        0.09
  18feb2010 |          2        0.02        0.11
  28feb2010 |          1        0.01        0.12
  09mar2010 |          1        0.01        0.13
  01apr2010 |          1        0.01        0.14
  01jun2010 |          1        0.01        0.15
  31jul2010 |          1        0.01        0.16
  01aug2010 |          1        0.01        0.17
  31aug2010 |          1        0.01        0.18
  01oct2010 |          1        0.01        0.19
  01nov2010 |          1        0.01        0.20
  01mar2011 |          1        0.01        0.21
  31jul2011 |          1        0.01        0.22
  19sep2011 |          1        0.01        0.23
  30sep2011 |          1        0.01        0.24
  01jul2012 |          1        0.01        0.25
  31jan2013 |          1        0.01        0.26
          . |      9,974       99.74      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Dec 2015