I had top score until someone got a score of 100001158 (mine being 3385. You may need to take extra measures to ensure the scores are valid and from the game.
The obvious flaw with this is people who just work out what your maximums are and then get the 100% score, but it discourages the ridiculous scores.
edit: one of your people said this below, disregard :-)
Edit: and now myself. I had accidentally typed the wrong id.