Have statistics take federal subjects in account

[Ainali]

The feature

Add more stats that show the richness of data on federal subject level.

Why?

Since #351 we now also have more levels than just countries, and we should show how the rich the data in Govdirectory is.

Examples and inspiration

No response

[Abbe98]

The data from federal subjects are taken into the counters, but the list could probably do with some smart listing so that subjects and countries aren't equally prominent.