There are five criteria set out in the Treaty of Maastricht that must be met by European countries if they wish to adopt the European Union's single currency, the euro. They are: 1) inflation of no more than 1.5 percentage points above the average rate of the three EU member states with the lowest inflation over the previous year. 2) A national budget deficit at or below 3 percent of gross domestic product (GDP). 3) National public debt not exceeding 60 percent of gross domestic product. A country with a higher level of debt can still adopt the euro provided its debt level is falling steadily. 4) Long-term interest rates should be no more than two percentage points above the rate in the three EU countries with the lowest inflation over the previous year. 5) The national currency is required to enter the ERM 2 exchange rate mechanism two years prior to entry.