Assuming each big leap in the ratings is a sale, over the 3 1/2 yrs on Amazon, I have sold at less than two a month. Can you tell me why I should stay there? I can see no reason. When you take into account three books had sales of several at a time, this brings the rate down even lower.
Before people respond with the usual reply about losing coverage, consider this. am I getting any coverage? All I will lose is less than $1 a month. Over the years on Amazon, their best month was this May with an exceptional number of 10 sales, this is below the worst month this year on Barnes & Noble (also this June) with 11.
What good is coverage, if it does nothing?
Another example is this blog, on average it gets about 200 readers a day,with over 300 posts read. But, it has done nothing for my e-book sales.
Remember. I don't use Twitter, of G+ groups, for the same reason, a lot of links, but no reaction. Again, I ask, what good is the coverage, if it does nothing?