Frequencies for first 10,000 rows of exp_dt_num variable in drug2007q4 dataset :

 Expiration |
date of the |
      drug. |
 (YYYYMMDD) |      Freq.     Percent        Cum.
------------+-----------------------------------
  31mar2006 |          1        0.01        0.01
  01mar2007 |          1        0.01        0.02
  26apr2007 |          1        0.01        0.03
  01jun2007 |          3        0.03        0.06
  26sep2007 |          1        0.01        0.07
  01feb2008 |          1        0.01        0.08
  01apr2008 |          1        0.01        0.09
  30apr2008 |          1        0.01        0.10
  01may2008 |          2        0.02        0.12
  31may2008 |          1        0.01        0.13
  01jul2008 |          2        0.02        0.15
  01aug2008 |          2        0.02        0.17
  08aug2008 |          1        0.01        0.18
  01sep2008 |          2        0.02        0.20
  31oct2008 |          1        0.01        0.21
  01nov2008 |          3        0.03        0.24
  01jan2009 |          1        0.01        0.25
  28feb2009 |          1        0.01        0.26
  01mar2009 |          1        0.01        0.27
  01apr2009 |          3        0.03        0.30
  01jun2009 |          1        0.01        0.31
  01dec2009 |          1        0.01        0.32
  28feb2010 |          1        0.01        0.33
  31mar2010 |          2        0.02        0.35
  31may2010 |          1        0.01        0.36
          . |      9,964       99.64      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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