Africa accounted for 12% of all net new mobile subscribers in Q1 2010

"Africa accounted for 12 percent of global mobile net additions in 1Q 2010, adding 20.1 million new subscribers to the world population of mobile users, and giving Africa a total of 480.2 million subscribers. This is a rather neat 10.0 percent of the some 4.82 billion mobile subscribers estimated to exist at the end of March 2010.
By comparison the Middle East accounted for 5 percent of global mobile net additions, clocking up some 8.1 million in the first quarter. Together Africa & the Middle East therefore accounted for 17 percent of global net additions.
According to research by The Mobile World, 1Q 2010 saw net additions of 168 million, taking the total to 4.82 billion. China and India remain the world's largest, and accounted for almost 28 percent of the global total at the end of 1Q 2010, but their contribution to the net quarterly gain in connections was double this at 56 percent. The USA accounts for 3 percent of net additions: the same percentage as Brazil and Russia combined.
With the world population at around 6.8 billion, the global mobile penetration rate stood at just under 71 percent at the end of Q1 2010. Africa, by comparison, had a mobile penetration of 47 percent, whilst the Middle East hit 86 percent."
Source:  Worldwide Mobile Market Growth, Africa and Middle East Telecom Week, July 2010