This is the typical argument used... I guess everywhere?
When immigrant/refugee goes on crime, rape & assault rampage, and someone points out his ethnic background, there follows near immediate response of how local major population does as much or even more of crime. And possibly with few examples. Of course, no shit sherlock: The major ethnic group causes major part trouble. But it's curious to check out how it may be that sometimes nearly non-existent minority can still cause almost equal volume of crime. It might be smaller, but compared to difference in size of population, outrageous. In some specialized fields, some population has nearly exclusive rights of operation.
Does it have ethnic/cultural root, is matter of debate, which hopefully won't happen here, hehe.. It has been going on forever and will go on.