Complex sentence: The only comparable places with Belgium are Catalonia, the Basque Country and Scotland, where there is majority voter turnout for local political parties, while national parties draw less (sometimes much less) than half of the votes.
Split into simpler sentences: The only comparable places with Belgium are Catalonia, the Basque Country and Scotland. These also have a majority voter turnout for local political parties, and national parties total less (or much less) than half of the votes.