I'm going to go with my gut
, which is right about 80% of the time.
Chances of:
Impeached, removed from office = 0%
Resigns during middle of term = 10%
Assassinated = 10%
Declines to run for second term = 10%
Fails in reelection bid = 20%
Reelected for second term serves full 8 years = 50%