As mortgage-holders struggle to adjust to a third straight interest rate rise, new research reveals how much the banks make from customers chasing the Australian dream.The Australia Institute says the big four banks - CBA, NAB, Westpac, and ANZ - rake in an average of $228,900 in profit over the 30-year span of an average $736,000 home loan.Last year, those banks' profits rose to a collective $43 billion pre-tax, $16.9 billion of which was paid …