Hmm... maybe this is too obscure. Almost the entire list is shown and people aren't getting it. That said, MartinLuther is on the right track. Think economy.
Members: Members: Ireland, France, USA, Italy, Britain, Great Britain, Germany, Russia, Mexico, Argentina
Non-Members: Saudi Arabia, Lebanon, Denmark, Canada, Australia, The People's Republic of Twolanguageistan, Zimbabwe, Vatican City, Ghana, Japan, Israel, New Zealand, Cuba, China