On January 1, 1999, the European Union implemented the Euro as a single economic unit and on January 1, 2002, paper and coin Euros came into circulation. Adopting the euro allows the economies of the "Euro-area" members to become more integrated. Currently, 19 of the 27 current EU members have adopted the Euro as their official currency and are part of the Euro Area. The most recent country to adopt the Euro is Lithuania, which adopted it in 2015. The remaining non-Euro-area member states were those who acceded to the Union after the euro was launched, but did not meet the necessary conditions for entry to the Euro-area and are considered "Member States with derogation".