http://www.demographia.com/dhi.pdf
The Demographia International Housing Affordability Survey uses the “Median Multiple” (median house price divided by gross annual median household income) to assess housing affordability. The Median Multiple is widely used for evaluating urban markets, and has been recommended by the World Bank and the United Nations and is used by the Harvard University Joint Center on Housing.
Australia
6.5
Canada
4.7
China (Hong Kong)
13.5
Ireland
3.6
New Zealand
6.7
United Kingdom
5.1
United States
3.2