The World Economic Forum says the United States tops the overall ranking in this year's Global Competitiveness report, followed by Switzerland and the Nordic countries. It says, in Sub-Saharan Africa, only South Africa and Mauritius feature in the top half of the rankings, with several countries from the region at the very bottom. Lisa Schlein reports for VOA from Geneva, where the report was released.

The report says the United States tops all other countries because it has the most sophisticated and innovative companies operating in very efficient markets. Senior economist at the World Economic Forum, Irene Mia, calls this a winning combination.

She says the United States also has an excellent university system and strong collaboration between the educational and business sectors, in research and development, gives it an edge over other economies.

"Overall the assessment is still number one, but we have to be careful," she said. There is also an index actually pointing to a potential problem in the long-term and the sub-prime mortgage is actually a reflection of that. There are serious micro-economic imbalances, which need to be addressed at some point."

Mia says the high level of U.S. debt and deficits is a concern.

The report looks at 12 different areas of competitiveness, to assess the strengths and weaknesses of a country's business climate. This year, more than 11,000 business leaders were polled in 131 countries.

The World Economic Forum sees the rankings as a way for countries to compare themselves with more successful economies and against their past performances to see how they can improve their competitiveness.

The report finds Europe, overall, is doing quite well in its business practices, as is the Asia -Pacific region. But, with the exception of South Africa and Mauritius, it finds sub-Saharan Africa lagging. Mia says this is largely because of Africa's many structural weaknesses.

"The quality of infrastructure; The quality and transparency of the public institutions; level of education; and, also what is a big weakness for Africa overall is the state of the health in general," she said. "It is still the (continent) with the lowest ranking in the main disease rates."

Despite its drop in this year's rankings, the report finds Botswana continues to be relatively successful, by regional standards. It is ranked 76th - the third best performance in sub-Saharan Africa. In contrast, Mia says Zimbabwe puts in a dismal performance. It is ranked 129 out of 131 countries. And, she says the situation is worsening.

"Micro-economy is not stable at all and this is a big concern," she said. "Spiraling inflation and the very high level of public debt and transparency of public institutions is a big concern."

The Report finds 95th ranked Nigeria has lots of potential, but is not taking advantage of its windfall oil revenues. It says it needs to upgrade the population's access to basic health care and education and to improve its infrastructure, if it wants to become truly competitive.