Frequencies for first 10,000 rows of rechal variable in drug2017q2 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,377       83.77       83.77
          N |        244        2.44       86.21
          U |      1,368       13.68       99.89
          Y |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 8 Feb 2018