ZenithOptimedia is predicting that global ad spending will grow 4.1 percent in 2013, reaching $518 billion, accelerating to 5.6 percent in 2015.

The gains will again be led by developing markets, which are expected to contribute 61 percent of ad spending growth between 2012 and 2015, increasing their share of global adspend from 34 percent to 37 percent. Developed markets will grow by just 2 percent on average, hurt by the Eurozone crisis. Ad expenditure is predicted to be much more robust in North American than in Europe, as consumer confidence, retail sales, job numbers and the housing market continue on an upward trend. Latin America is also set for rapid growth, alongside Eastern Europe, Central Asia and "Catch-up Asia" (China, India, Indonesia, Malaysia, Pakistan, Philippines, Taiwan, Thailand and Vietnam). Even with the growth of developing markets, the U.S. is still the largest contributor of new ad dollars. Between 2012 and 2015 the U.S. is expected to contribute 28 percent of the $76 billion that will be added to the global adspend.

Read more http://www.worldscreen.com/articles/display/2012-12-3-zenithoptimedia-global-ad-spending