What percentage of sub-Saharan Africa’s workforce is under 24-year of age: 25%, 35% or 40%?

35% - 40%
Young people between 15-24 year of age constitute between 35% and 40% of the workforce in most sub-Saharan African countries. An additional
one-fourth of the work force is between 25 and 34 years old. Every year, roughly 11 million young Africans are entering the labor force. (source:
Yeboah, Kwame, and T. S. Jayne. 2018. Africa’s Evolving Employment Trends, Journal of Development Studies, 54(5))

so What?
The world will experience unprecedented demographic shifts during the 21st century. The share of the world’s population living in sub-Saharan Africa (SSA) will have risen from 12% in 2015 to 36% in 2100. Under the most favorable projections, only a quarter of these new
African workers over the next decade will find wage jobs. Agriculture and the informal sector will need to
absorb most youth into gainful employment or Africa and other regions of the world will face escalating
challenges resulting from youth under-employment.