Secondary education is essential for individual children to achieve their full potential, and for nations to advance social and economic development.

However, only 12 developing countries and territories have secondary school participation ratios of 90 percent or more.
Globally, only 55 per cent of children of the appropriate age attend secondary school. In Africa, that number drops to less than 30 per cent. The poorer a child’s household, the less likely the child is to attend secondary school.

Source: UNICEF global databases, 2009, and UNESCO Institute for Statistics Data Centre, March 2009

Reference: http://www.childinfo.org/education_secondary.html