Frequencies for first 10,000 rows of rechal variable in drug2016q3 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,351       83.51       83.51
          N |        175        1.75       85.26
          U |      1,454       14.54       99.80
          Y |         20        0.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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