A young couple starts a college-savings fund for their newborn baby and invests $20,000 in a broad market index fund and $10,000 in a high-growth index fund. Historically, the annual return of the broad market index fund follows a normal distribution with an average return of 6.73% and a standard deviation of 2.36%. The annual return of the high-growth index fund is also normally distributed with an average of 9.12% and a standard deviation of 4.19%. Develop a Monte Carlo simulation model to show the annual balance of the college-savings fund until the baby turns 18 years old.