No, I have no references at all. I'm saying that eleven events is hard to draw meaning from, a wide range of things could cause that to happen and it's not necessarily a sign of a problem.
Per capita, there are 4-5 times as many people shot in the cities of Sweden as in Norway, Denmark and Finland. And mainly by criminals from those suburbs. So there are quite a lot of data.
Google this yourself, but I suspect you know all this already.