Our method
Where the numbers come from, how they are computed, and what happens when something changes.
Sources
Calculations
Reuse
The charts and figures on 21radar are free to reuse, including commercially. The site name printed on the image is enough attribution: no link is required and no permission needs to be asked. The data is published under a Creative Commons BY 4.0 licence, and this page stands as explicit permission to attribute by the mention “21radar.com” alone.
Updates
Data is fetched automatically every three hours and committed to the project repository. Every update therefore leaves a timestamped trace: no past figure can be altered without it showing.
Every number on 21radar comes from a public source and is recomputed from verifiable data. This page says which ones, and how. If a method ever changes, the change will be written here and dated.