Illustration: Simon Letch "We've never felt demand like we have right now," he said. A 2016 global wealth report by property firm, Knight Frank, said the number of ultra-high net worth individuals - those with net assets of $US30 million ($40.5 million) or more – has grown by 135 per cent in Australia over the past decade. Sydney is now rated the "world's eighth-most important city" for people in that wealth bracket. Knight Frank estimates there are now 842 people in Sydney with net assets of $US30 million or more and another 588 in Melbourne. There's been similar growth in the number of Australian billionaires. A record 53 were included on last month's BRW rich list this year compared with 22 a decade ago. A study by Caroline Freund and Sarah Oliver from the Washington-based Peterson Institute for International Economics has examined key characteristics of the world's billionaires, including Australia's growing band. It draws on two decades of data from Forbes' annual world's billionaires list.

Illustration: Simon Letch The Peterson Institute study says extreme wealth is increasing rapidly, despite slow global income growth. The latest global rich list includes a record 1826 US-dollar billionaires. One striking trend has been the surge of extreme wealth in emerging countries, especially China where the number of billionaires rose from 64 to 213 between 2010 and 2015. The ultra-rich in developing nations are no longer concentrated in the "resource and politically connected sectors of the past". Instead, a large and growing share of billionaires, especially in east Asia, have made their fortunes creating new and innovative products. The demography of billionaires is also starting to change. The latest list has more under-40s and more females than ever.

But perhaps the biggest shift over the past two decades has been the rise of self-made billionaires. Self-made wealth accounted for nearly 70 per cent of billionaire wealth in 2014, up from 45 per cent in 1996. The finance sector and tech companies have contributed to the growth in self-made billionaire wealth, especially in the US. The Peterson Institute study estimates 28 per cent of Australian billionaires inherited their wealth, which means Australian billionaires are more likely to be self-made than their European counterparts where 36 per cent inherited their fortunes. But Australian billionaires are much less likely to be self-made than in China where only 2 per cent of billionaire wealth is inherited. There are other marked differences across regions and countries. In emerging markets robust economic growth rates mean the average wealth of the five richest citizens is not growing as quickly as GDP. But in many advanced economies, especially a grouping of "Anglo countries" investigated by the researchers (consisting of US, Canada, Australia and New Zealand), extreme wealth has been growing faster than GDP. This helps explain why economic inequality is being so hotly debated in those nations. It turns out Australia has a disproportionate share of the world's billionaires. We have about 0.33 per cent of the global population but account for 1.8 per cent of all billionaires, the research shows. And its finance and property - not mining - that has created more Australian billionaires than any other industry. The Peterson Institute paper says 31 per cent of all Australian US dollar billionaires in 2014 made their fortunes primarily in the finance and property sectors. That's more than three times the proportion in Europe (10 per cent) and well above the US (27 per cent). The advanced country average for the proportion of billionaires who made their fortuned in finance and property was 20 per cent.

Some economists think the world's billionaires will become increasingly clustered in large markets over time. Such a pattern is evident in Australia where the BRW rich list shows 33 of our 53 billionaires are based in either Sydney (17) or Melbourne (16). There's another distinctive trait of Australia's ultra-wealthy: they seem to really like living here. Knight Frank's wealth report says only 6 per cent of ultra-high net worth individuals in Australasia want to change their country of residence over the next decade – the equal lowest proportion of any global region. Australasia also had the lowest proportion of super-rich families sending, or planning to send, their children overseas for either secondary or tertiary education. So much for a class war. Ross Gittins is on leave.