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

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,539       95.39       95.39
          D |        389        3.89       99.28
          N |         12        0.12       99.40
          U |         51        0.51       99.91
          Y |          9        0.09      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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