Frequencies for first 10,000 rows of exp_dt_num variable in drug2010q4 dataset :

 Expiration |
date of the |
      drug. |
 (YYYYMMDD) |      Freq.     Percent        Cum.
------------+-----------------------------------
  31jan2010 |          1        0.01        0.01
  05dec2010 |          1        0.01        0.02
  01jan2011 |          1        0.01        0.03
  31mar2012 |          1        0.01        0.04
          . |      9,996       99.96      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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