Katherine Lim purchased a condominium for $50, 000 in 1987. Her down payment was $20, 000. She financed the remaining amount as a $30, 000, 30-year mortgage at 7%, compounded monthly. Her monthly payments are $200. It is now 2007 (20 years later) and Katherine has sold the condominium for $100, 000, immediately after making her 240th payment on the unit. What is her effective annual internal rate of return on this investment?