Countries age based on their mental maturity and not by time. Because of this, they don't have birthdays.
How does their ages work exactly?
Well, if a country grew up in a neutral environment, they'll age like a normal human.
Of a country grew up in a peaceful and less traumatizing environment, they'll take their time growing up.
If a country grew up in a stressful environment, they'll be forced to grow up faster.
The youngest countries in this ENTIRE roster is South Sudan, Kosovo, and Montenego
