Ah, apologies, I misunderstood. I don't recall seeing anything usefully quantified in the article about the effects of tax incentives, though there was a commen

Ah, apologies, I misunderstood. I don't recall seeing anything usefully quantified in the article about the effects of tax incentives, though there was a comment somewhere there about negative gearing, quoting David Llewellyn-Smith: "This tax policy allows more than one million Australians to engage in a negative carry into property in the hope of capital gains. In a nation of just 24 million, 1.3 million Australians lose an average of $9,000 per annum on this strategy thanks to the tax break". As to determining which is the most significant factor, I will leave that to those with far greater understanding of the area than mine.