While generally speaking suburban areas contain more and more population as compared to 'traditional' centres - the ancient cities are stabilising - on the other hand this 'plus' factor shows a qualitative difference from one country to another. ###>Si en gros les périphéries rassemblent de plus en plus de populations que les centres "traditionnels" - les villes anciennes se stabilisent - par contre ce "plus" qualitativement diffère de pays en pays.