Like everyone else here, I don't have any data (I searched, but couldn't find anything), only anecdotes - my own experiences from living in Cologne and Berlin,

Like everyone else here, I don't have any data (I searched, but couldn't find anything), only anecdotes - my own experiences from living in Cologne and Berlin, and those of friends who live in Hamburg, Frankfurt, Munich, etc. There are issues everywhere but Berlin is particularly bad. We weren't even able to hold a regular election without messing it up.