Even for showing fraction of a whole, pie charts can be deceptive because humans aren’t all that great at comparing areas of different sectors of a circle. (Although this one isn't exactly a pie because of the empty center.)

But here there’s a more fundamental issue with this chart: Why would you want to focus on what fraction a country represents of the 5-country total? It doesn’t even tell us what fraction they are of the world total, which we might care a bit more about. And it totally obscures whether a country's total nuclear output went up or down. It also doesn’t capture how the countries nuclear power generation changed relative to that country's total power generation.

Two charts that would probably be more interesting/useful:

1. Show 5 lines showing how each countries electrical energy from nuclear plants changed over time. That would still capture relative movement of the countries, while also showing whether their total use of nuclear energy was going up or down. (Plus i could see the whole thing at once, instead of having to wait for the animation😊)
2. Show 5 lines for each countries percentage of electricity from nuclear (out of their total electricity usage) over time. So whereas the first chart shows changes in how much nuclear energy they use (e.g., are they building plants or shutting them down) this second chart shows whether nuclear’s “market share” in the country goes up or down” (e.g. if nuclear is growing slower than other electricity sources in the country, the nuclear is becoming relatively less important to their overall ability to meet their energy needs).

I'm really not trying to beat up on OP here. This sub gets a lot of these questionable visualizations, and they all make the same kinds of misteps. So I'm hoping this advice helps someone.

As a general guideline, one can ask what question about the data does this visualization answer, or what observation about the data does this visualization convey? And you would want that to be a question or observation you think is important or useful and you'd want to choose the visualization that makes that answer or observation clear to the user.

As a second general guideline, ask whether an animation conveys something you wouldn't get more simply from a static image with time as one of the axes - or if the animation just gives you the same information more slowly. If it's the latter, you're better off without it.

Applying those to this chart, I don't think what the visualization shows is more meaningful than what it obscures, and what it shows could have been conveyed more straightforwardly with a static chart.