When former Chinese Politburo member Zhou Yongkang was arrested in 2014 on corruption charges, the scale of his ill-gotten gains was astounding, totalling some $16bn. When sums that large are involved most of the assets have to be invested in financial instruments and real estate.

But the list of physical currency found in his homes is revealing: 152.7 million Chinese yuan (valued at the time at $24.5m), 662,000 Euros, 10,000 British pounds, 55,000 Swiss francs - and $275m.

The former head of China's internal security services and one of the 10 most powerful men in China apparently preferred to keep his "petty cash" mainly in US dollars.

He's not alone. China lost around $1 trillion to capital flight in 2015, before clamping down hard at the beginning of 2016. Much of this money leaves China via fake invoicing in Hong Kong, where the local currency is pegged to the US dollar. Illicit outflows are also facilitated by casinos in the Philippines, South Korea, and on remote Pacific islands, all of which operate primarily in dollars.

Predictions of the dollar's demise, and eventual replacement by the Chinese yuan, are a staple of global economic punditry, but they have little basis in reality.