As previously mentioned, the World Census occasionally changes the way it measures things—usually because of flaws discovered in the old methodology, as revealed by a few extreme cases.
These recalibrations are posted for public preview ahead of implementation on the World Census Beta page, so that nations can provide feedback. A batch have completed this process, and will go live in the next few days!
Beta 004 affecting Weaponization
Beta 005B affecting Black Market
Beta 006 affecting Lifespan
Beta 008A affecting Income
Beta 010 affecting Agriculture-based Industry
Beta 015 affecting State-Owned Industry
Beta 016 affecting Economic Efficiency
Most nations won't notice any change. But you might, especially if your nation is very unusual. In those cases, you will see an abrupt change in some of your World Census ranking scales as the new system is adopted.
If you're interested in what might be coming down the pipeline, a new round of betas has also just been made public! Previews are now available for: