Diminishing Discount Calculation from Base Rent

We have a scenario where the Base Rent is decreased by a discount for the first three years after which there is no discount. Here is the scenario

Base Rent is 10,000

First Year Discount of 15% so net base rent after discount is 8500

Second Year Discount of 10% so net base rent after discount is 9000

Third Year Discount of 5% so net base rent after discount is 9500

Fourth and Fifth Year, there is no discount so the base rent is 10,000

What is the efficient way to achieve this programmatically in Property Manager?