I would recommend reconsidering Wikipedia (ie. the Wikimedia foundation) since they have large reserves of money and their fundraising is misleading.

Wikipedia editors even sort of had a „revolt“ against the foundation because of the misleading fundraising banners.

Source

I recommend writing a log of donations. Then you can look at where you donated, when and how much, and remind yourself of where you want to send money again.

Now, I am pretty lazy. So it's just my_donations.txt, open with Vim and whip out that calculator. Should probably be a spreadsheet instead. I don't know if Calc let's me do math based on key (place of donation).
I guess I could have separate columns per key (to maintain log nature), then do subtotal per key to specific cells, then grand total from those cells.
Still begs the question of how I would do that per year.
Sperate columns each year?
Just make range selection at the end of year?
To be honest, I never actually used any spreadsheet software. I suppose there might be some logic, if so, there sure would be a way to check the date column on same row as amount.

But anyway, Vim + calculator. 👍