What is a good rating

[WeShallUnclench]

You need to consider the (probably very pertinent) fourth reason readers may not vote: they click on the story, read a few sentences, it doesn't grab them for whatever reasons, and they leave. They never get to the point of voting.

I took that as included in point 1, but yeah. The harsh reality is that "number of people who voted" might aproximate "number of people who actually read it".