When talking about server statistics:
http://www.warcraftrealms.com/activity.php?serverid=-4
http://www.warcraftrealms.com/census.php?serverid=-3
It will be good to split PvE and PvP to EU and US:
All EU PvE
All EU PvP
All US PvE
All US PvP
Thats because there is big diference in player base, who plays on PvE and PvP, and EU and US. And often players choose only one ruleset, and they are not interested in statistics about other ruleset for choosing, when to create character.