An account has a balance of 4,500 on 1/1/2015. Three months after 1/1/15 the balance was 4,030 just before a deposit of 400 was made. Eight months after 1/1/15 the balance was 4,710 just before a withdrawal of 200 was made. On 12/31/2015, the balance was 4,990. Find the actual yield rate (no approximation)