Although the European Union has legislated in the area of energy policy for many years, and evolved out of the European Coal and Steel Community, the concept of introducing a mandatory and comprehensive European energy policy was only approved at the meeting of the informal European Council on 27 October 2005 at Hampton Court. The EU Treaty of Lisbon of 2007 legally includes solidarity in matters of energy supply and changes to the energy policy within the EU. Prior to the Treaty of Lisbon, EU energy legislation has been based on the EU authority in the area of the common market and environment. However, in practice many policy competencies in relation to energy remain at national member state level, and progress in policy at European level requires voluntary cooperation by members states.In 2007, the EU was importing 82% of its oil and 57% of its gas, which then made it the world's leading importer of these fuels. Only 3% of the uranium used in European nuclear reactors was mined in Europe. Russia, Canada, Australia, Niger and Kazakhstan were the five largest suppliers of nuclear materials to the EU, supplying more than 75% of the total needs in 2009.