By contrast, growth in export volumes in Sub-Saharan Africa averaged only 2 percent per year, in part because world trade of the products they export grew at half the rate of growth of world trade.
与此相反,撒哈拉以南非洲地区的出口额增长每年平均仅有2%,部分原因是他们所出口的产品的世界贸易额增长速度只有整个世界贸易额增长速度的一半。