Searching for statistics I have found a lot of areas with pro-capita GDP above 30.000$ (Bavaria of Germany, Inner London, Luxembourg...). I also found regions with values between 10,000 and 15,000, that are quite low (large areas in Spain,Portugal,Greece,Southern Italy,Eastern Germany...). Such differences are astonishing, considering that rich areas have unemployment firmly below 5%, while the poorest usually have more than 15% (and sometimes 21%) of their workforce unemployed. First, Europe must enhance mobility A LOT.
I have found a lot of papers on the argument but no detailed statistic , by now.