Economic growth is set to slow in Sub-Saharan Africa to 3.7 percent this year, its weakest pace since 2009, mainly due to the drop in commodity prices.According to World Bank report the region's economy, which grew 4.6 percent last year, will strengthen only marginally in the next two years.Commodity-dependent economies from Zambia to Nigeria have suffered this year from the price rout of commodities like copper and oil, triggering currency falls that forced policymakers to tighten interest rates in response.