Global mobile 3G subscribers in Q4, 2012 was estimated at 23%. As at Q2 2013, the figure stood at 24.55%. That means that the majority of people in the world have no access to 3G/4G yet. In Africa, the figure is likely to be even lower.
Here in Nigeria, for example, where all four GSM operators run 3G networks, outside of the largest cities and a few smaller ones, 3G services do not exist. Everywhere else, subscribers have to make do with GSM/EDGE for mobile data.
What Are The Implications?
If you develop websites, mobile apps and mobile internet based services, you need to factor this information into your work. If you are looking to sell devices too in predominantly 2G areas, this bit of information is vital. All other things being equal, 2G devices are more affordable than 3G devices and will do well in many markets outside of 3G areas, especially in low income environments.