According to this article Berlin seems to be a strange capital city when it comes to debt:
In almost every European country the capital is the engine of the economy. But a new study shows there is one exception to this rule.
The study by the Cologne Institute for Economic Research looked at how severely the income per head in a country would be hit if it had to survive without its capital. The results showed that across Europe, capital cities were the focal points of their countries’ economies.
If Berlin were cut adrift from the rest of the Bundesrepublik, the average German would become 0.2 percent wealthier.
In 2015, the capital received €3.61 billion in subsidies, the most of any of the German states. The majority of this money came from wealthy Bavaria, which paid €5.45 billion of the total €9.6 billion which rich states gave to poorer ones, ARD reported in March.
I am wondering why this exception?
Question: Why does Berlin have debt issues in opposition to many other European capital cities?