It depends on the coin age. Coin age, as I understand it, is set to 0 each time the coin is either staked, used in a tx or mined. After 30 days the coins are matured and can be staked. They will produce coins based on their coin age vs. the network weight. In other words, the longer your coins are in your wallet the faster they will generate your PoS coins. 5% is the minimum. Nobody has ever said what the maximum is though. My ~50k flutter staked for about ~7-8k after the first month of actual staking. It's hard to say exactly how much I generated as a percent though, because the coins all came in over the course of a month or so.