This BBC piece http://www.bbc.co.uk/news/uk-politics-eu-referendum-35990076 claims to fact check the government's pro EU pamphlet. Here's an extract:
'The claim: Less than 8% of EU exports come to the UK while 44% of UK exports go to the EU.
Reality Check verdict: That's true, although looking in percentage terms makes UK trade look less important to the EU. In cash terms, the UK in 2014 exported £227bn worth of goods and services to other EU countries and imported £288bn from them, which makes the UK look like a much more important customer for the rest of the EU.'