10. Cabo Verde
Percentage of youth of total population: 21.5%
Cape Verde, or Cabo Verde as the natives call it, is a tiny island nation with a population of merely 521,000. The average age of the citizens of this humble country is 24.5 years, an optimal age structure of a nation. Then again, it’s much easier to maintain the age of an entire population when it’s so small. However, the UN does not expect even Cape Verde to maintain the age of its people. The current average fertility rate per woman is 2.37, but it is expected to fall to 1.94 by the year 2030, in keeping with the trend that most countries seem to be following now.