It should be close to zero.
I looked it up last year from German data...from the Wall period (1990) to 2013, it typically ran about 250,000 a year on immigrants from non-EU countries and asylum seekers, with exception years (Balkans war period). In the two Balkan periods...around 750,000 each period came in....roughly half of those who came in....left within two years returning to the Balkans.
They can generally handle about this number of 200,000....taking into account their passports/IDs were verified prior to entry and people were farmed out to various states, with the states able to handle the traffic flow.
So their immigration policy isn't exactly open except for certain types, if you catch my drift.