After the Berlin Wall came down, how long did it take for East Germany to catch up with West Germany?
The parts of Germany that used to be East Germany have still not caught up to what used to be West Germany. That means that more than 20 years have not been enough to get East Germany caught up to the west.
There are at least two reasons for this. First, the East German economy was devastated by its decades as a communist economy. It lacked the kind of experience with capitalism that was needed. Second, knowing that the west was much better off than the East, many of the most talented Easterners moved to the West once this was possible.
For these reasons and others, the former East Germany has not caught up to the West.