The behaviour of mainland tourists attracts an awful lot of interest around the world, but it is their spending power that is absolutely eye-popping. And it will only get bigger. Last year mainlanders pumped the equivalent of Bangladesh's GDP into the cash registers of airlines, shops and hotels worldwide. By the end of this decade, their spending will be closer to that of Hong Kong's GDP - an economy roughly 20 rungs higher than Bangladesh on the World Bank's rankings. "With over 73 per cent of mainland Chinese in the 10 to 60-year-old bracket, just looking at this structure on its own, China should have 1.1 billion travellers in the next 10 years," reckon analysts at Bank of America/Merrill Lynch.