The absence of a "cladestine conspiracy" can never be proven. However, there are indications that powerful EU governments don't want another failed state on their borders:
They want Turkey to hold refugees back.
A significant number of their citizens (and voters) have Turkish roots.
The pre-accession process is stalemated but not formally ended.
Yes - this is available directly from the Turkish Supreme Electoral Council here.
The data for German consulates in particular have been analysed further in Germany's Turkish Voters - What Do We Know? by Thomas Krumm from the Turkish-German University, in which he provides this chart:
He also calculates the Spearman's rank correlation coefficient between ...