The European Union concentrates nearly half (43%) of productive activity in a space:

  • bounded by a line connecting London, Paris, Milan, Munich, and Hamburg;
  • covering 14% of the EU's territory;
  • where one third of the EU's population lives. 

The figures are from the European Union, and are mentioned in an overview of European regional policy.

As with much center-periphery social science research, I'm not sure how much weight or importance to give to these statistics. Here are a couple of observations:
  1. The pentagon described above is centered on the historic core of the European Union (France, Italy, Germany, Netherlands, Belgium, Luxembourg), plus the south of England. In other words, subsequent enlargement has been to the periphery, not to the core.
  2. Does regional policy really do anything? The answer would seem to be no, if we give weight to this center-periphery analysis. There's plenty of data supporting the positive contribution of regional development funds –in other words that support the proposition that regional policy really does something– which would seem to undercut the relevance of this center-periphery analysis.
I'd also recommend an excellent resource: the EU's Eurostat office has released its 2008 regional yearbook, available for free as a pdf, in English, French, and German.