I've heard that Netflix started with a 1-10 scale, and then moved to a five-point scale (which is the one I first remember.) Then, 2-3 years ago, they went to a simple 2-point thumbs up/thumbs down scale. Last year they switched to a three-point scale (don't like, thumb up, two thumbs up).

Based on the October dataset, and restricting ratings to just the Modern Era (post-2009), 91% of all ratings submitted by Phish.Net users were a 3, 4, or 5. We're just like Netflix.