The Republic of Ireland is the official description of the sovereign state which covers approximately five-sixths of the island of Ireland, off the coast of north-west Europe. The state's official name is Ireland (Eire), and this is how international organisations and citizens of Ireland usually refer to the country. It is a member of the European Union, has a developed economy and a population of slightly more than 4.2 million. The remaining sixth of the island of Ireland is known as Northern Ireland and is part of the United Kingdom. Ireland is the fastest growing country in Europe, with a population increase of 8.1% between 2002 and 2006, or 1.97% annually.