Source: World Resources Institute, EarthTrends 2006 and World Development Indicators 2009, Washington, D.C., World Bank, 2009 (www.wri.org/project/earthtrends).
Source : World Resources Institute, EarthTrends 2006 et World Development Indicators 2009, Washington, D.C., Banque mondiale, 2009 (www.wri.org/project/earthtrends).