The Viewability Benchmarks figures from ad verification company Meetrics were based on the definitions produced by the Media Rating Council and the Internet Advertising Bureau (IAB), namely that at least 50% of an online ad appears in the visible area of the browser for at least one second. Impressions triggered by fraudulent activities were excluded from the benchmark.
In the UK, viewability levels for display ads dropped from 52% in Q3 to 50% in Q4 2015. In Germany the decline was slightly larger, from 61% to 58%, while France saw a four percentage point fall, from 69% to 65%, and Austria a five point slide from 70% to 65%.
"After a bit of a rally, things seem to be getting worse again," noted Anant Joshi, Meetrics' Director of International Business.
"Although in the UK, for example, the drop isn't much, it's the direction that's more important," he said.
"Current efforts to address the issue don't seem to be working – either that or the efforts in one area are simply offsetting the inevitable falls generated by more automated buying."
Joshi added that in the final quarter of 2015, some £134m was wasted on unseen banner ads alone.
In terms of particular formats, half-page ads were the most viewable format in the UK (63%), followed by billboards (59%) and MPUs (47%); leaderboards were the least viewable format (43%). The average time viewable ads were in view was 31.4 seconds in the UK.
The report further revealed that, over the last couple of years, the average amount of a web page taken up by advertising was just 8%.
"The ratio between advertising and editorial is much lower than you'd think – particularly with all the talk about online ad clutter," Joshi said.
"On a web-wide level, it's simply a myth."
Data sourced from Meetrics; additional content by Warc staff