Complex sentence: According to the 2011 census, the total population of the United Kingdom is around 63,182,000--the third-largest in the European Union (behind Germany and metropolitan France) and the 22nd-largest in the world.
Split into simpler sentences: According to the 2011 census, the total population of the United Kingdom is around 63,182,000. It is the third-largest in the European Union (behind Germany and metropolitan France) and the 22nd-largest in the world.