Let me explain it further. The official name for the ratio is called housing price-to-income ratio. You can google it. It measures the affordbility of the housing price in each country. It can be applied in each country. For example, if the average annual income in us is around 5W usd for ordinary people, and the average housing price is 25W usd. Then the ratio would be 5 which means it is still in the reasonal range between 4-8. Any number higher than 8 means the housing price in that country is quite unaffordable. To my latest knowledge, the ratio in Australia is around 8, Japan is around 6. But the number in china is around 20 or even 50 for some people. For me, arrogant people seem to be dangerous.