If it seems the EU referendum debate just involves two politicians shouting contradictory statistics at each other - then we are here to help. In this series, we're giving you a break from the politicians and we're going to try to figure out the truth. Bracing concept, isn't it? We'll be looking at some of the big questions - the cost of being a member, immigration, regulations and trade. But today we're looking at lawmaking. Tim Harford asks how much UK law comes from the EU and are we always being outvoted on what to implement?