The European Union's GDP (gross domestic product) at market prices is the highest in the world, with the UK having the second largest share in it. 

The per capita gross national income of the UK in 2014 was much higher than the per capita income of the entire EU.

Its contribution to the EU Budget is significant. 

The net contribution is much less than the gross, as the UK gets a rebate and a public sector receipts from the EU.

Goods and services exports to the EU are less compared to imports from the EU in 2015.

UK's net stock assets in EU was much higher compared to the EU's in the UK in 2004 but the equation was reversed in 2013.

UK, a crucial partner in EU trade

Photograph: Marcelo del Pozo/Reuters