> At the moment it there is an 'electoral event' field, not a year field. It only contains the value 'municipal 2011'. I can split that into year and election type?

I think just one field to categorise the event will be enough for now, but that's up to you. My primary concern is that we're explicit about which election event to show data for, so we don't bake in the assumption that everything is for 2011.