Frequencies for first 10,000 rows of rechal variable in drug2015q1 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |        276        2.76        2.76
          D |      9,179       91.79       94.55
          N |         58        0.58       95.13
          U |        475        4.75       99.88
          Y |         12        0.12      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 19 Apr 2017