Wowser... you have a tenuous grasp on statistics at best...
Please provide a source that 20% of any given area in Germany is Muslim. A source being, someone with any amount of reputation and ability to investigate demographics in Germany who then compiled said information into some sort of document...
Who is encouraging German women to date foreigners?
"According to the 2006 figures from
Germany's Federal Statistics Office,
Turkish men accounted for 14% of foreigners married to German women, followed by
Italians and
Americans.
[376] Conversely, German men marrying non-German women primarily choose
Polish women, with
Russian, Turkish and
Thai women following in roughly equal numbers.
[376]
Comparative sociologist Amparo Gonzalez-Ferrer argues that one of the main reasons why Turkish men marry Germans more than Turkish women do is due to
Islam permitting men but not women to marry non-Muslims.
[376] Dirk Halm,
political scientist for the Center for Turkish Studies in
Essen, remarked that considering Turkish citizens make up 25% of all foreign residents in Germany—not counting an additional one-third ethnic Turks who are German citizens—intermarriage rates in Germany are "in reality very low".
[376]"
https://en.wikipedia.org/wiki/Interracial_marriage#Germany
Seems like you might need to more worried when I come to visit Germany. Watch out, Olga.