Frequencies for first 10,000 rows of exp_dtstr variable in drug2012q4 dataset :

   Expiration date of the drug.Multiple |
                        dates possible. |      Freq.     Percent        Cum.
----------------------------------------+-----------------------------------
                                        |      9,998       99.98       99.98
                               20100420 |          1        0.01       99.99
                               20110630 |          1        0.01      100.00
----------------------------------------+-----------------------------------
                                  Total |     10,000      100.00

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