Mary and Steve are both exactly 20 years old. Mary will deposit $1000 at the end of every year for the next 40 years, until age 60, into her retirement fund. Steve is going to wait until age 40 to begin his savings. In order to try to catch up to Mary, Steve will deposit $2000 at the end of every year from age 40 to 60. Note that by age 60, both Mary and Steve will have contributed $40,000 into their respective funds.

a. Calculate how much Mary and Steve will each have at age 60 if they each earn 4% compounded annually on their investments.

b. As a percentage of Steve's total, what percentage more does Mary have in her retirement fund at age 60?