Frequencies for first 10,000 rows of rechal variable in drug2015q4 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,116       91.16       91.16
          N |        123        1.23       92.39
          U |        747        7.47       99.86
          Y |         14        0.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 6 Apr 2017