Opera has released its latest State of Mobile Advertising report which sees iOS regain its position as the top mobile platform based on advertising impressions, after Android took the crown during its previous report for the fourth quarter of 2012.

The leap-frogging between the two rival operating systems demonstrates how little difference that there is terms of numbers between them on Opera’s advertising network — which was brought under one umbrella in February when Opera Mediaworks launched. The company dedicated ad business serves 50 billion ad impressions per month across its network of 12,000 sites and applications, bringing in $400 million of publishing revenue in 2012, up from $240 million in 2011 — that makes it a platform worth analysing.

Apple’s iOS also dominates on monetization, generating the highest average eCPM rate and bringing in the greatest share of revenue from publishers: 44.54 percent in Q1 2013, up from 41.91 percent. Android comes in second, with 31.36 percent — up from 30.94 percent — some margin ahead of the rest of the field.

Interestingly, Opera has begun breaking out traffic share for Android tablets because they have grown into “a small but noticeable share of the market”. However, the iPad continues to win out over its rival tablets and it now accounts for 6 percent of ad impressions to Opera’s 300 million plus monthly users, and an impressive 12 percent of total network revenue.

Another device that saw impressive growth was the Samsung Galaxy S3 which — despite the impending launch of the Galaxy S4 — drove 11% of all Android traffic, up from 9% last quarter. The launch of BlackBerry 10 also boosted BlackBerry (named here as RIM) which grew from 4.23 percent of Opera’s traffic share to 6.19 percent, with its monetization growing too.

Here’s how the stats compared quarter-by-quarter.

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Elsewhere, the company found that its Music, Video and Media category dominated ad volumes (29 percent of all requests) and revenues (17.7 percent), although its Business and Financial content enjoyed the highest revenue per impression.

Looking worldwide, Opera identified Europe — notably the UK, Italy, Germany, France and Spain — as its fastest growing marketings. Indeed, the share ads from the Opera Mediaworks network served in Europe came in at 21.5 percent, up from 15 percent in Q4 2012, though the US remains its largest market. The US accounted for 50.7 percent of impressions which, though down from 60 percent, translates into a dominant 75 percent of all revenues.

The quarter was another record one for the mobile advertising industry. Summing it up, Mahi de Silva, CEO of Opera Mediaworks, said:

Mobile advertising, which is expected to exceed 10% of all digital advertising this year, will become a vital facet of every major ad campaign in the upcoming year. The size of the audience combined with rich media and engagement rates shows we will continue to see a shift of ad dollars away from traditional media and desktop digital media to tablets and smartphones.

Headline image via Opera