Spending on Internet ads will overtake billboards and other outdoor advertising in 2007, and close the gap on radio in 2008. The Internet will account for 6.5% of all advertising by 2007, according to Zenith Optimedia. Online ad spending accounted for 4.5% of the global market in 2005. Radio’s market share will fall to 7.9% in 2008, from 8.5% in 2005.