People who hold a savings account at ABC Bank will receive a different interest rate for each year 2020 2025. On the 1st January 2020 the schedule is: 2020 2.50% 2021 2.50% 2022 3.50% 2023 3.50% 2024 4.00% 2025 4.00% On any date after 1st January 2020 the schedule can be changed. One rate, some of the rates or all of the rates could be updated. For example, on 25th May 2020 the schedule is: 2020 3.00% 2021 3.00% 2022 3.50% 2023 3.50% 2024 4.00% 2025 4.25% It is only possible to have one schedule for any given day (the schedule is never different at different times within one date).

Please suggest the design of a database table/tables which could be used to store the interest rate schedules. You may want to optimize for minimal disk space or for ease of querying. The most common query will be to retrieve the most recent schedule. Please describe why you have chosen your design and what you chose to optimize for. We are not expecting a full implementation. Instead, your submission should focus on the key aspects of the design, and is expected to fit on one side of an A4 page.