European regional GDP per capita in 1900 and 2010 (relative to the EU average). Source: Rosés and Wolf https://books.google.ie/books?id=XTr3DwAAQBAJ&pg=PR15&dq=%22relative+gdp+per+capita%22&hl=en&sa=X&ved=2ahUKEwiRxuvsoOXtAhXiuXEKHVZnAYIQ6AEwAHoECAQQAg#v=onepage&q=%22relative%20gdp%20per%20capita%22&f=false
That's Luxembourg (Belgium) not Luxembourg (Luxembourg) by the way.
Ten European regions with the highest GDP per capita in 1900, 1938, 1950 and 2010 https://www.cesifo.org/en/publikationen/2018/working-paper/regional-economic-development-europe-1900-2010-description