Sie fragen sich, wie hoch die Zahl in Deutschland wäre? „…die Einwanderung machte 25 % des Pro-Kopf-BIP Spaniens und 10 % der Sozialversicherungseinnahmen aus, aber nur 1 % der öffentlichen Ausgaben.“

From what I can see, the quote comes from Pedro Sanchez, but he hasn’t clarified what he means by these figures, so it’s impossible to construct an analogous statement about Germany. If one wanted to make such a statement, an in-depth study would have to be conducted, as many many effects of immigration would have to be considered even if you have a specified scope.