Frequencies for first 10,000 rows of exp_dt_num variable in drug2008q1 dataset :

 Expiration |
date of the |
      drug. |
 (YYYYMMDD) |      Freq.     Percent        Cum.
------------+-----------------------------------
  01dec1998 |          3        0.03        0.03
  30oct2007 |          1        0.01        0.04
  22jan2008 |          1        0.01        0.05
  17feb2008 |          1        0.01        0.06
  31mar2008 |          1        0.01        0.07
  01apr2008 |          2        0.02        0.09
  01jul2008 |          2        0.02        0.11
  01sep2008 |          1        0.01        0.12
  18oct2008 |          1        0.01        0.13
  22oct2008 |          1        0.01        0.14
  27oct2008 |          1        0.01        0.15
  31oct2008 |          1        0.01        0.16
  01nov2008 |          4        0.04        0.20
  24dec2008 |          1        0.01        0.21
  25dec2008 |          1        0.01        0.22
  29dec2008 |          1        0.01        0.23
  31dec2008 |          1        0.01        0.24
  28feb2009 |          1        0.01        0.25
  31mar2009 |          2        0.02        0.27
  01may2009 |          1        0.01        0.28
  30jun2009 |          2        0.02        0.30
  31jul2009 |          1        0.01        0.31
  28aug2009 |          1        0.01        0.32
  01dec2009 |          1        0.01        0.33
  31mar2010 |          1        0.01        0.34
  30apr2010 |          1        0.01        0.35
  28feb2011 |          1        0.01        0.36
  01oct2011 |          1        0.01        0.37
          . |      9,963       99.63      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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