When Gavin was born, his grandparents started a savings account for him with a beginning balance of $350. Every month they deposited $45 into the account. The savings account paid an annual interest rate of 2.1%, compounded monthly. Gavin just turned 24 and the balance of his account is now $17,411.69. How much of the money in Gavin's account was earned in interest? (Round your answer to the nearest cent, and don't include units.)