Somehow I doubt the statistics for Germany. Maybe 10 out of my 160 contacts on StudiVZ are using Facebook.
I thought the same thing. It's probably because the rankings come from Alexa and Google Trends: the former is useless, and the second is unrelated to number of users.
The ex-USSR part of the siatistics is accurate, it would be correct to say that odnoklassnini is close #2 everywhere where vkontakte is #1 and vice versa.
Livejournal is a blogging service, not a social networking one, thus it should be listed separately.