Be aware that statistics on wage levels, unless provided by the people who pay them, are notoriously one of the least reliable sets of figures that governments publish... usually only a small proportion of people will actually answer salary questions, and there is no way of verifying their answer.
Add to that (at least in Ireland) use of fairly out-of-date occupation and sector categories (and for an EU-wide survey you have to use lowest common denominator/most obsolete of course...).
Then there's a problem where because of the possibility that someone could be identified if location and sector and occupation are given in enough detail to be useful, which national statistical bodies must always avoid, and the result is that what is available tends not to be terribly useful...
HR companies do surveys but they are usually quite small sample and also it's information which they regard as commercially sensitive so it isn't usually available in any detail in the public domain. A good place to try is professional associations or employer bodies (but both may have agendas for inflating or deflating figures).
All the best
Imogen