At the start of the year, the European single currency celebrated its 10th anniversary. It also faced its biggest test to date.

As the financial crisis intensified, investors began to worry that some eurozone countries might default on their debt – driving up their bond yields to the point where some analysts suggested the single currency could even break up. This is because a default could have put pressure on a country to leave the eurozone as stronger economies objected to the likely negative impact on the euro and potential extra costs of bailing them out.