Note that when you're talking about a planet, education is going to vary widely especially if its a big planet. Taken as a whole, the earth could be said to have a large amount of substandard educational levels for example. So, the educational levels given in the books aren't as helpful as they might be. (And figuring out educational levels even in teh real world can be difficult-- do you weight, for example, the highly educated elite higher than the outback peasants?).