Greece was the only country with a mixed picture of the benefits brought by the EU, the study said.
Denmark and Germany came out as the winners of the European Union's single market in a study released on Monday.
For every year between 1992 and 2012, Danes’ average annual incomes were €500 (3,730 kroner) higher than they would have been without the single market, a study by the German think-tank Bertelsmann Foundation found. The income increase was the highest of the 15 countries that joined the single market in the 1990s.
That means in 2012, GDP per person was 2.0 percent higher than it would have been without integration – the second highest figure of the EU countries.
Only Germany’s 2.3 percent increase was better, but the Danes’ average €500 per capita income gain was higher than the Germans’ €450 increase.
The single market guarantees free movement of goods, persons and services, as well as of capital and payment transactions across national borders.
The study found that economic integration increased in almost all of the 15 states that joined the European single market in the 1990s, resulting in income gains in every national economy.
Only Luxembourg was not assessed because of "major data gaps".
Taken alone, Greeks' annual incomes rose by an average of just €70 each year over the 20-year period.
Yet in real terms, incomes were found to have fallen by €190 in this time due to the nation's dramatic economic crisis.
The United Kingdom has also failed to take as much advantage of the single market as it could have. Incomes in the UK rose an average of just €10 a year thanks to the single market.