No, because that would be taking a sample of 100 players, he is basing his statistics on the entire population of RuneScape.
Umm...
2% could be considered a ratio - 2 Pmods : 98 normal players. This ratio will stay constant if you scale it up. Say you take a sample of 1,000,000 players (no idea how many signups runescape has, I'm not going to attempt to guess) - 20,000 of these players would be Player moderators. I doubt there is anywhere near that many PMods in RS, and I am very sure there are more than 1 million signups (there was a point in time where RS once had 1 million people playing simultaneously.)


