IEA (2020), Average annual change in primary energy intensity improvement, historically and in the Sustainable Development Scenario, 2010-2040, IEA, Paris https://www.iea.org/data-and-statistics/charts/average-annual-change-in-primary-energy-intensity-improvement-historically-and-in-the-sustainable-development-scenario-2010-2040, Licence: CC BY 4.0