Assuming that I have an average lifespan, and assuming an average
length of tenure for each, then by the time I die I will have been a
contemporary of…

  7 Popes
  9 Archbishops of Canterbury
 17 US Presidents  
 15 British Prime Ministers
  3 British monarchs

Of course, this depends a lot on entirely unpredictable variables, but
it’s an interesting list!