GroupM forecasted that global ad spending will increase 4.5% ($534B) this year over 2013, and will increase an additional 5.0% in 2015 to $560B (exceeding pre-crisis peak of 2007/2008 in real terms). Spending in the U.S. is expected to increase 3.4% in 2014 and another 4.2% in 2015 to $168.3B. 17 markets account for 93% of expected ad growth with the U.S. accounting for ¼ of incremental ad dollars. - Link