Gabriel Zucman, one of 3 French economists who in recent times have published extensive research on wealth and equality, in a book, ‘The Hidden Wealth of Nations: The Scourge of Tax Havens,’ published this month, estimates that 8% of the world’s financial wealth — some US$7.6tn — is hidden in tax havens such as Switzerland, Bermuda, the Cayman Islands, Singapore, Luxembourg and Ireland. Oxfam in a report published last January said that in 2013 the number of billionaires holding the same amount of wealth as the bottom 50% of the global population of 7bn was at 92.