Area data as of end of 2021.

[bgrundmann]

From destatis (Bodenflächen + one column from Siedlungsflächen) - areas we are not interested.

See: https://github.com/GermanZero-de/localzero-generator-core/blob/0420ebc24e6d1a95a315762bf2a340f6f999afa6/exploration-and-data-generation/tooling-data-prepration/area.py#L51