Starting from Albert's birth, his parents deposit a constant amount into a savings account at the beginning of each month to save money for Albert's college tuition. The last deposit is made one month before Albert's 18th birthday. Suppose the college tuition is $20,000 per year for four years. The first tuition payment is due on Albert's 18th birthday. Suppose the savings account pays an annually compounded interest rate of 4% per year, how much is the monthly deposit made by Albert's parents