Frequencies for first 10,000 rows of rechal variable in drug2004q2 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,247       82.47       82.47
          D |      1,455       14.55       97.02
          N |         39        0.39       97.41
          U |        225        2.25       99.66
          Y |         34        0.34      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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