What is a "share rate"? What is a "share rate" one can find in a mining pool dashboard?

I understand what a hash-rate is, and how that applies to myself (miner), as well as to the pool or the network. I also understand to some degree what shares of a block being mined are. But what is then the shown share rate (shown as a value between 0 and 1, as well as in shares/s).
Depending on which pool your mining, this is usually representative of how many valid shares are being passed back to the pool.

It has been displayed in a decimal fraction it seems, so 0.985 would be an amount of 98.5% valid shares returned.