What is over 50%? 51% or 90%? How many of those “black” are refugees, asylum seekers, immigrants? 

I think 15% is high or disproportionate unless asylum seekers and refugees are more than 15% of German population. 

Here is USA 🇺🇸 example: over 50 percent of homicides are committed by blacks 

Bell_curve

“According to Germany's Interior Ministry, 27 illegal migrants either committed or attempted to commit murder or manslaughter in 2017.
The 447 figure used by AfD actually refers to all asylum seekers and refugees, most of whom are in Germany legally.
Overall this group was 15% of the total 2,971 suspects linked to these crimes in Germany last year.”

15% is not “overwhelming”, or? I am not saying immigrants do not commit crime either.