Willem said:
While I respect your personal opinions and decisions on this, I would like to advise you on changing your scale. If you think an 'average' book deserves a 7.5 you've been very lucky in your reading material You've probably got reader's bias (you're reading stuff you know you like, meaning your scores will be on the high end anyhow). I'm predicting a lot of 8-8.5-9 scores which honestly doesn't make for a very interesting list. Compare tv.com, where people can rate episodes of shows. Usually, episodes will score very, very high over there because it's mostly fans rating them. Fans will often rate a bad episode higher than deserved, because, well, they're fans.
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Your point?
I'm not lucky about my reading material. I'm mostly picky about it. So what if I have reader's bias? The score is based on my entertainment value.