Frequencies for first 10,000 rows of dechal variable in drug2009q1 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,526       95.26       95.26
          D |        223        2.23       97.49
          N |         38        0.38       97.87
          U |         51        0.51       98.38
          Y |        162        1.62      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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