Eurid, the registry operator for .eu, have released a report in relation to how registrants register their .eu domain names ie. if you are based in country X, are you more likely to use a registrar based “in country” or go overseas?
The results show that 65% of registrants stay with a domestic registrar, 18% choose another registrar in the EU, while 17% choose a registrar from outside the EU.
The results are probably a bit biased, as some of the largest registrars in terms of reseller networks are from outside the EU and probably account for a very large portion of the non-EU registrar sales. Whether the registrants are even aware of this or not is an entirely different matter.
Further information is available on the Eurid site.