From this article in the Financial Times
when 15 to 29-year-olds make up more than 30 per cent of the population, violence tends to happen; when large percentages are under 15, violence is often imminent. The “causes” in the name of which that violence is committed can be immaterial. There are 67 countries in the world with such “youth bulges” now and 60 of them are undergoing some kind of civil war or mass killing.
Read the whole thing.