David Jone's estimated net wealth is $15,000, and he intends to retire in ten years. His annual salary after tax is $40,000 and current expenditure is $28,000, allowing him to save $12,000 per annum (Assume that this money is saved at the end of the year). His pension fund advisor tells him that the actuarial evidence suggests he should plan on an expected life of 16 years following retirement. If the rate of interest he can earn on invested funds is 8%, and David wants to maintain a minimum wealth position of $50,000 after the expected 16 years of retirement, how much does he have at the beginning of retirement?