Spoiler :
Immigrants from X country to Germany.
I already guessed that

Immigrants from X country to Germany.
It looks like it's the part of nuclear power in the country's electricity production.
But if it's related to Germany, I'd say it's the amount of trade between Germany and the coloured countries (export or import percentages or total maybe ?).
I mighta expanded on that by saying German-made nuclear power parts. But Iran isn't shaded.
Pearl harbour had a lot of casualties, right?
Yes it does!
Just kidding. You never completely shut down the nazi guesses.
Anything to do with the German language?