Westpac yesterday reported growth in credit assets of 5.9 per cent for the quarter, or 23.6 per cent over a year.A "change in risk profile" explains 90 basis points of this; rising demand the rest.This growth rate is about as high as at any time since the mid 2000s lending boom, and is pretty high.(This assumes data from the new "Pillar 3" disclosures are comparable to the balance sheet-based method of reporting credit that has prevailed for many years.)Westpac lifted its estimate of impaired loans across all lending categories.The bank put impaired loans at $930 million, with 74 per cent from corporate loans, with the three worst loans also the most famous; ABC Learning, Allco and Babcock and Brown.Nine per cent of impairments are mortgages. The bank said most troubled loans were in New Zealand.Should Australia follow New Zealand, expect troubled mortgage loans to jump; there's a 22 basis point gap in quality to catch up on, and five times the population.For every dollar of new provisions for normal, new lending, Westpac said it was setting aside four dollars to cover problem loans.