For the third time in four years, the Mo Ibrahim Foundation has declined to give out its award for excellence in African leadership.

The foundation announced in London Monday that it would not present the $5 million award. It said none of the leaders it considered for the prize this year met the criteria.

The award is given to an African leader who was elected democratically, excels in office and then leaves office when his or her term is completed.

Mo Ibrahim, the British-Sudanese businessman who created the foundation, told reporters that the award committee does not want to compromise its standards.

The award has been given out only three times since it was established in 2006, most recently to former Cape Verde President Pedro Pires in 2011.

The foundation also released its annual Index of African Governance on Monday. It said overall governance has improved in Africa over the past decade.

For the second year in a row, Mauritius was rated the best-governed country in Africa, followed by Cape Verde, Botswana, Seychelles and South Africa. Somalia was at the bottom of the list.