GDP of Germany: $3.7T (2017)
GDP of Spain: $1.3T (2017)
GDP of Greece: $0.2T (2017)
GDP of Europe: $19T (2019)
If Germany's economy declines 5%, it has declined the amount of the entire Greek economy. This is one reason the Greeks were pretty strident during their financial crisis; the amount of money they lacked was crippling for them and irritating for the Germans.
A five percent decline in Germany is a one percent decline in the broader Eurozone. It's been suggested that the European Union was a back-handed way of ensuring continued German superiority by locking the currency float. The numbers certainly support it. If Germany is in decline (and make no mistake: Germany is in decline), then the European Union is in decline.