I liked to visualize data like this. In the beginning, especially before 2012, we can see that mining was more decentralized when miners where "Unknown". I believe this Unknown are more decentralized, probably many small independent miners.
I do not agree with the designation of centralization, there is no Mining pool that can control more than 50%, so we are now more decentralized than in the past. You can call the situation currently distributed, but it is decentralized.
Also, the unknown does not mean random pools, so perhaps these same people control these unknown pools.
Generally, the presence of the unknown is a good thing, but it is better that you cannot control more than 50%.
I like it, your animation makes it clear how quickly quickly mining pools gain and lose market share.
It will soon differ with Binance's entry into this market
[1]. We will see many changes happening soon.
I'd love to see a similar animation on the top 15 cryptocurrencies over time, if you can find the data.
@OgNasty has some old data ---> Historic Bitcoin Exchange Rates (since July of 2010)
[2][1]
https://pool.binance.com/[2]
https://bitcointalk.org/index.php?topic=5254496.0