Gartner has released some research findings that indicate consumers will spend $6.2 billion in 2010 in mobile application stores. Meanwhile, advertising revenue is expected to generate $0.6 billion worldwide. According to Gartner, mobile app stores will exceed 4.5 billion downloads in 2010, eight out of ten of which will be free. Gartner also forecasts worldwide downloads in mobile application stores to surpass 21.6 billion by 2013, and free downloads to account for 82% of all downloads in 2010 (87% in 2013).