Belgium has a free-enterprise economy, with the majority of the gross domestic product (GDP) generated by the service sector. The Belgian economy also is inextricably tied to that of Europe. The country has been a member of a variety of supranational organizations, including the Belgium-Luxembourg Economic Union (BLEU), the Benelux Economic Union, and the EU. The first major step Belgium took in internationalizing its economy occurred when it became a charter member of the European Coal and Steel Community in 1952. On January 1, 1999, Belgium also became a charter member of the European Monetary Union, paving the way for the introduction of the euro, which became the country’s sole currency in 2002, replacing the Belgian franc.