Help me!

Rating: 5/10 (28 February 2002)

What's going on here? At the moment I am writing these words The Shawshank Redemption is 3rd in IMDb's all-time top250. I don't think the movie is particularly bad, but to rank it even in the Top50 is a crime against a lot of brilliant film makers further down the Top250 and even more people whose works don't even appear on the list!
So now I ask if anybody can please explain to me: 1) Why is this movie's average rating over 9? Does it appeal to some basic American sense of justice and love of happy endings? 2) Why did more than 65.000 people rate it? I'm pretty sure it wasn't nearly as commercially succesful as The Lord of the Rings or the Godfather with about 50000 votes. Did it do well on video in the US?
And if you REALLY feel like watching movies about people behind bars why not give Cool Hand Luke or the 1974 classic(!) Caged Heat a try?
I don't mean to demean The Shawshank Redemtion or anything, but I just don't get it's massive rating. Is this one of the most overrated movies of all time? Well, according to the statistics of this, the odds are that you do not think so. But would you then please be so kind as to explain it to me. Feel free to email me.