Frequencies for first 10,000 rows of rechal variable in drug2008q4 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,637       96.37       96.37
          D |        288        2.88       99.25
          N |         12        0.12       99.37
          U |         45        0.45       99.82
          Y |         18        0.18      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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