Economic inequality in the United States can be summed up in a single figure: 1 per cent. That refers to the super-rich at the top whose distance from the rest has widened in recent years. In the EU, the key number is 11 per cent, the unemployment rate. As more workers find themselves in prolonged spells of joblessness across the troubled continent, the rich-poor divide widens. This risks not only hampering growth, but also turning inequality into a politically explosive issue.