Complex sentence: Starting with the town of Arenys de Munt, over 550 municipalities in Catalonia held symbolic referendums on independence between 2009 and 2011, all of them returning a high "yes" vote, with a turnout of around 30% of those eligible to vote.
Split into simpler sentences: Starting with the town of Arenys de Munt, over 550 municipalities in Catalonia held symbolic referendums on independence between 2009 and 2011. All of the towns returned a high "yes" vote, with a turnout of around 30% of those eligible to vote.