On January 1, 2007, Europe celebrates the fifth anniversary of the launch of euro notes and coins by welcoming a thirteenth member of the eurozone – Slovenia, the tiny former Yugoslav republic. But the eurozone’s geographical expansion is modest in comparison with the rapid growth in euro notes in circulation within the region and beyond.

Earlier this month, the value of euro notes pushed through the €600bn (£402bn; $787bn) level – roughly double the value of the then-national currencies in circulation at the end of 2001. The signs are that in December the currency came of age by overtaking the US dollar in terms of the value of notes in circulation. The figures used for the comparison by the Financial Times include notes held in the vaults of commercial banks but exclude reserves of notes held by central banks.