We speak to Uzodinma Iweala, the CEO of top business magazine Ventures Africa, which has released its annual rich list of the continent's top earners. Nigeria is dominating the line-up. Leading the 55-member-strong billionaires' club once again is Nigerian manufacturing magnate Aliko Dangote, valued at almost $26 billion. Uzodinma Iweala tells us what the dominance of Nigeria's wealthy say about Africa's economic landscape.