There is no winner this year for the world's most valuable individual prize - the Mo Ibrahim prize for good governance in Africa.The $5m (£3.2m) prize is supposed to be awarded each year to a democratically elected leader who has voluntarily left office.There was also no winner in 2009 and 2010 because the panel said there had been no suitable candidate.Last year, Cape Verde President Pedro Verona Pires was named.He led the fight against Portuguese colonialism, introduced multi-party politics and was praised for living standards.The $5m prize is spread over 10 years and is followed by $200,000 a year for life.Previous winners were Botswana's President Festus Mogae and Mozambique's Joaquim Chissano.Sudan-born telecoms entrepreneur Mo Ibrahim says the prize is needed because many leaders of sub-Saharan African countries come from poor backgrounds and are tempted to hang on to power for fear that poverty awaits them when they leave office.