Is the middle class the key to Africa's future?

The African Development Bank has published a report claiming that 1 in 3 Africans is a member of the middle class. The report suggests that Africa's strong economic growth over the past two decades is a result of an emerging middle class and that this group is critical to the continent's positive political development.
But what is the middle class? The bank defines the middle class as those who spend $2-$20 a day. Members of the African middle class are likely to be people who have a salaried job or who own a small business and who have fewer children. They may pay for private health care and education.