Another interesting article from ABCDiamond:

Ratio of House Price to Incomes for Average Workers Sydney

An indication of the real increase in property prices is the median property priced set against the median household income of those groups that actually purchase properties.
For that reason, rather than using the national average wage, which includes all part time wages, 16 year old workers etc., I have used a household income calculated on a household with one full time income and one part time income.
Property to Wage ratios for Sydney, New South Wales.

more information and charts can be found on here: Ratio of House Price to Incomes for Average Workers Sydney : ABCDiamond