That is probably because Twitter is not really popular in Germany. Looking at the numbers [1] I am still surprised because I would have expected something even lower not knowing a single active Twitter user personally.
I'm aware that German translations of English sentences are about 30% longer, but by that logic Twitter should only be popular in countries with logographic or ideographic writing systems like Twitter is in Japan.
jatorre's assumption that location is deactivated seems to be an appropriate explanation.
Love that we see some tweets from some pretty remote places in Africa - Botwana, Zambia and Malawi. Mobile phones have some pretty big penetration there, but internet connection is still not too strong (texting is far bigger).
CartoDB[1] allows you to put your data on top of rich base layers. Use Mapbox or any other basemap provider. You can even create maps without a background.
Their Javascript library code is on Github[2], and they encourage people to collaborate. But it doesn't seem to have a license, I couldn't find one in the repo.
might also be due to the fact that Turks are simply - really mad about soccer :)! I lived couple years in Istanbul, and was amazed by how Turks are obsessed with soccer overall.