There aren't many reliable sources on the subject. I ended up using a data set provided by the OECD. The data covered a few dozen countries, which was great, but it didn't include France nor the United States. I was very interested in data for these countries and did some additional research. Eventually, I decided not to include them as I couldn't guarantee that the methodology from other sources would be comparable to that of the OECD's. As far as the design of this piece is concerned, I knew right from the start that I wanted to create a series of small multiples in rectangular shapes. I hence dove straight into the Figma Design software and played around with shape size, colour and shadows until I was satisfied with the result.