EU countries: Ireland, Austria, Germany, Belgium, Luxembourg, the Netherlands, France, Spain, Portugal, Greece, Italy, Finland, Sweden, Denmark and the UK.
The last three do not use the euro as their currency, but participate in the union. So the 12 who do use the euro are called the euro 12 as opposed to the EU 15.
This year will be the third in succession that the economies of the EU 15 have in aggregate outperformed the Euro 12.
So if the EU 15 is the Euro 12 with the addition of Sweden, Denmark and the UK, then won't the EU 15 always outperform the Euro 12? Or maybe they are talking about the fact that the three countries that haven't yet adopted the Euro are outperfoming the 12 countries that have.