Percentages are probably not the best way to elicit well-calibrated guesses about very probable or very improbable events. (The difference between 1/1,000 and 1/1,000,000 is a lot bigger in reality than it looks, when you put them both between 0 and 1 on a scale of 0 to 100.)

None of the questions in the survey sound to me like ones where one could easily get more than 99% sure of (outside an argument)

Eliezer's own "Finale of the Ultimate Meta Mega Crossover" describes a scenario (admittedly fanciful) in which one would be hard pressed to answer the "simulation" question with a simple yes or no.

Thanks for the spoiler. ;-|