The energy data are derived from the International Energy Agency (IEA) World Energy Balances (https://www.iea.org/data-and-statistics); and from the United Nations Energy Statistics Database (http://data.un.org/Explorer.aspx?d=EDATA). GDP data are primarily sourced from the International Monetary Fund (IMF) World Economic Outlook database, complemented with data from the World Bank World Development Indicators and the CEPII CHELEM databases.