Blue is real GDP as a percentage of Euro area real GDP (indexed at Q4 2007=100), red is nominal GDP as a percentage of Euro area nominal GDP (indexed at Q4 2007=100). Note that, for Italy, nominal GDP was consistently stronger in relative growth than real GDP, especially before 2004, while in Germany, nominal GDP was consistently much weaker in relation to the rest of the Euro area than real GDP until the 2008 financial crisis, after which they both became tightly linked. In fact, for Italy, nominal GDP was so strong that as a share of Euro area nominal GDP, it continued rising until 2004, while for Germany, real GDP was so strong that it grew as a percentage of Euro area real GDP from 2005 to 2008, and continued growing at this same trend (with the exception of the Great Recession, which impacted German real GDP unusually strongly) until the end of the graph, while German nominal GDP as a share of Euro area nominal GDP actually shrunk between 2005 and 2008. This, my friends, is the supply side in action! You can’t realistically hope to see it much more clearly than that. Italy is sclerotic and did terribly even when its demand side was good; Germany is resilient and did surprisingly well when its nominal income performed terribly. In fact, even though its nominal GDP as a percentage of Euro area nominal GDP in late 2013 was far lower than the same in 1999, its real GDP as a percentage of Euro area real GDP was even higher than in late 2013 than in early 1999!
In conclusion, have a free labor market, kids.