Gross domestic product (GDP) is a measure for a country’s economic activity. It refers to the monetary value of all end goods and services produced by an economy in a determined period. The volume of GDP per inhabitant in Purchasing Power Standards (PPS) is expressed in relation to the European Union (EU28) with the average set to equal 100. If the index of a country is higher than 100, this country's level of GDP per inhabitant is higher than the EU average and vice versa.

The data are expressed in Purchasing Power Standards (PPS), which enables elimination of the differences in price levels between countries allowing meaningful volume comparisons of GDP between countries. The index, expressed with respect to EU-28 = 100, is intended for comparisons between countries rather than for temporal comparisons.