We're sort of speaking about different things. I know what a normal distribution is, what I'm saying is that when they design the test (and it's redesigned frequently as IQ tends to collectively change over time) they do so in a way that they hope the mean, mode and average is 100. If you score 100 you are considered exactly normal, no more, no less.

The test doesn't look at other results to make the comparison, that's something we do. The test is flawed and so realistically the mean, mode and average are likely to be different from 100.