How to get 20% coin / year ?
Leave your coins for a year, you can even not open the wallet for a year and then open it and it would have gained enough weight over that period of time to stake fairly quickly + earn 20% interest on that inputs balance.
What do you mean? , for staking the wallet need to be open 24 hours....
why do you say that he can keep the wallet close?
Because contrary to popular believe you don't need to have your PC running 24/7.
Your coins gain weight regardless...
It only solves a block though if it is running.
So if you leave your coins to gain weight and turn your PC on later down the line, you will get most of your rewards over that year all at once based on your weight.
this actually happen to me when i opend my wallet being closed for 4 hours by accadent i got a few tranactions