Hey, have you found countries added to the world just a few years ago?! Post them here. Kosovo was added in 2008, South Sudan was added in 2011, that's all I can think of.
Sealand is a micronation (To be accurate, a sea ford just outside of Britain's waters, which was claimed by an army Major), which are nations that are trying to gain status as new countries. No one has though. And it's not new, been around for a while.