I don't see where to define how much is saved per year.
Check out cash-flow priorities.
During each simulation year, excess income is computed based on your income, expenses, debt payments, taxes due, and other variables, then flowed through the cash-flow priority system.
By default, anything left over after that is saved in cash, but you can alternatively choose to “spend anything left over” if that aligns better with your personal budgeting philosophy.