GroupM has revised its biannual advertising spend forecast for 2013 down to $507 billion, estimating growth of 3.4% this year rather than the 4.5% originally estimated in December of 2012.

The revised forecast, which is published in the media company’s “This Year, Next Year” report, is a result of measuring 75 countries. Continuing economic issues in Europe, particularly in Italy, Spain, Portugal, Greece and Ireland are listed as the primary reason for the downgrade, according to a release. The report adds that the Eurozone is expected to post an 11% drop in measured advertising for 2013.

As for 2014, GroupM is predicting global ad spending will increase 5.1% over 2013, representing $533 billion worldwide.

Canada is expected to have its overall media ad spend grow by 2% in 2013 versus 2012 numbers, with 1.9% growth over this year currently being forecast for 2014. Some of the headlines impacting numbers in Canada include newspapers currently taking up 28% of media revenue share, far exceeding the platform’s use in consumers media day usage and the potential for DSPs to change online trading and lower costs, according to the report.