Wireless data traffic is expected to grow 66% a year for the next five years. That means, by 2017, monthly mobile data traffic will reach 11.2 exabytes per month, or 13 times what it is right now. Other data points in the report underscore how big the mobile world has become and how quickly it will grow to be much, much bigger. Last year, some 4.3 billion people around the world had mobile devices, a population that will grow by close to a billion in five years.