What is Germany's ethnic structure?

Germany is a country that used to be ethnically pretty
homogeneous but which is now becoming much less so.  The change in Germany's ethnic
makeup has been the cause of a fair amount of tension within the
country.

According to the CIA Factbook (link below) Germany
is 91.5% German.  This is a large percentage, of course, but Germany's Turkish and
Muslim population is growing rapidly.  Turks currently make up 2.4% of the population of
Germany and Muslims make up 3.7%.

The fact that there is a
relatively large population of people with a different ethnicity and religion has caused
problems.  Germany is currently struggling to figure out how to integrate ethnic Turks
into the German population.  Up to this point, they have been largely excluded, but they
are becoming a bigger portion of the society and Germans are starting to feel that they
must be assimilated.