Every major media category is set to see global revenues shrink this year, as only online is poised to end 2009 on the plus side, ZenithOptimedia said in the media agency’s latest forecast. Worldwide, online will be up 9.2 percent, Zenith said, revising its July prediction of 10.1 percent growth for the segment. Most of this growth is coming from paid search and other up-and-coming formats. The agency zeroed in on the performance of online sub-categories, where more granular data is available. That breakdown has paid search up by 20 percent this year, while online video grows 19 percent, social media’s up 45 percent and mobile gains 69 percent. To be sure, the actual dollar amounts in those subcategories remain relatively small.