How has population growth affected the Sub-Saharan Africa region?

The population of sub-Sahara Africa has grown from 186 million to 856 million people from 1950-2010. That's about 11 million people a year for the past 60 years or approximately 670 million people in 60 years. By 2060, the population of sub-Sahara Africa could be as large as 2.7 billion people.