It is too plentiful for small economies to spend, and has therefore added to the glut of global saving that is in part responsible for the financial excesses of recent years.

ECONOMIST: Gulf economies

In 2005 Ben Bernanke, now chairman of the Federal Reserve, pointed out that global interest rates were oddly low, suggesting a glut of saving abroad, not a shortfall of saving at home, was responsible for the flow of capital to America.

ECONOMIST: Global imbalances