Frequencies for first 10,000 rows of dechal variable in drug2005q1 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      7,409       74.09       74.09
          D |      1,559       15.59       89.68
          N |         97        0.97       90.65
          U |        617        6.17       96.82
          Y |        318        3.18      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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