5.4% — That's the share of household income now going to mortgage interest payments, higher than the 5.7% peak of 1989 when lending rates hit 17%. But here's the kicker: today's mortgage rates are only about half that. The culprit is Australia's super-sized home loans — the average mortgage has ballooned to $735,000, up $75,000 in a year. KPMG's Terry Rawnsley says the total debt burden is heading toward 6% once this year's three RBA rate hikes fully...