Sydney, Melbourne and Adelaide have won the dubious new accolade of “impossibly unaffordable”, with buyers having to fork out a median nine or more times annual household income to secure a median-priced home, in the latest Demographia International Housing Affordability report.

In its 20th edition, the annual ranking has introduced the new term to describe cities where housing purchase is extremely expensive relative to income, topping its previous highest superlative of “severely unaffordable”, applied where the price-to-income ratio topped 5.1.