We combine data from the most reliable sources we know of into one coherent dataset, where no country or years is missing. As with all such numeric exercises and guesswork, the end result is not perfect. There’s always doubt. Keep in mind that the purpose with Gapminders data crunching is to create the missing big picture based on the best available evidence. Our purpose is not to provide data for numeric analysis. Our data is created to put fact-based pictures in peoples minds, to replace pictures created form myths or fantasies. We fill in all the gaps so that our visualisations will not visually flicker when countries come and go because of missing data. Reducing the visual distraction let anyone see the big movement of world history from 1800 up till today. We stretch the trends into the future to show what the world will look like in case things continue along the current lines, which nobody knows.