Economic development was spurred in the late 19th century with the opening of the state's first casino, the Monte Carlo Casino, as well as a railway connection to Paris. Since then, Monaco's mild climate, scenery and gambling facilities have contributed to the principality's status as a tourist destination and recreation centre for the rich. In more recent years, Monaco has become a major banking centre and has sought to diversify its economy into the services sector and small, high-value-added, non-polluting industries. The state has no income tax, low business taxes and is famous for being a tax haven. Over 30% of the resident population are millionaires, with real estate prices reaching €100,000 ($116,374) per square metre in 2018. Monaco is not formally a part of the European Union (EU), but it participates in certain EU policies, including customs and border controls. Through its relationship with France, Monaco uses the euro as its sole currency; prior to this it used the French franc. Monaco joined the Council of Europe in 2004 and is a member of the Organisation internationale de la Francophonie (OIF). It is also the host of the annual street circuit motor race Monaco Grand Prix, one of the original Grands Prix of Formula One. The principality has a club football team, AS Monaco, who compete in the French Ligue 1 and have become French champions on multiple occasions. A centre of research into marine conservation, Monaco is home to one of the world's first protected marine habitats, an Oceanographic Museum and the International Atomic Energy Agency Environment Labs, which is the only marine laboratory in the United Nations structure.