Basically Eurostat trade data for individual EU member countries with China seems to have some substantial artefacts probably because most EU imports from China arrive in Dutch ports, even though their ultimate destination is probably all over the EU. It's hard to explain otherwise the huge figure for Dutch imports (and thus trade balance) from/with China relative to Dutch population, economy, etc.
Are there any data sources or papers that try to adjust for this Rotterdam effect, i.e. figure out where those Chinese imports are really headed in the EU (and adjust the trade figures per member country accordingly)?
(Thanks to Henry for pointing out the right term.) Eurostat actually acknowledges the issue in a FAQ, but does not try to quantify it:
The quasi-transit is known to impact mostly the Member States with big ports at the external border to the European Union and in particular the Netherlands. This is why its impact on figures is known as the ‘Rotterdam effect’. In case of imports, the goods destined to other EU Member States arriving in Dutch ports are recorded, according to Community rules, as extra-EU imports by the Netherlands (the country where goods are released for free circulation) and as dispatches from the Netherlands to the Member States of actual destination even though there is no link with economy of the Netherlands.
The quasi-transit is known to impact more the imports but exports are also affected. In exceptional cases, the customs clearance occurs not in the actual Member State of export but in the Member State of exit, i.e. in the Member State from which the goods are taken out of the EU customs territory.