What is the ROI of owning Ether after entering POS?

Question

It's from my understanding you make ETH by owning ETH during POS. And assuming that is true how will ROI be determined?

Answer 1

At EDCON Vitalik said that the max ROI you can get is 5% per year.

See here at minute 11.

Answer 2

Not sure of exact amount, I read somewhere but do not recall where that it was possibly 15% ROI staking 15 ETH.