To create the interactive maps, we first researched what data was available on each fossil fuel. The goal was to find the most up to date and reliable data available. We selected our sources based on reliability. Countries release their data at different intervals, so to ensure accuracy we selected confirmed figures from reliable sources such as the U.S. Energy Information Administration (EIA) and the Central Intelligence Agency (CIA), among others.
The majority of our figures come from 2018 and 2017 and were the most up to date figures available from trusted sources.
Oh, and while we are at it: global energy demand grew yet again in 2018, by 2.3%, its fastest pace in ten years. 70% of that was provided by fossil fuel, and only 30% by renewables and nuclear. While the developed world is switching from coal to natural gas, the developing world sees coal as their savior. Just the growth in fossil fuel last year exceeded the growth in renewables over the same time period.