Opera Software has released its first State of Mobile Advertising report, based on insights from its mobile ad platform 4th Screen, using data mined from a global network of over 35bn ad impressions during Q2, 2012.

Its findings were good news for rich media ads – between January and June 2012, the number of HTML5 rich media ads on the platform nearly doubled, from 28 per cent to 51 per cent. Standard mobile ad executions, meanwhile, dropped from 35 per cent down to 21 per cent.

Rich media also saw better customer engagement. Ads with video content saw an average dwell time of 52 seconds – and 66 per cent of users that click through complete the interaction. Though fewer users (48 per cent) will interact with them, rich media ads with photo-taking capabilities saw the highest dwell time, at 1 minute 25 seconds.

The highest average eCPM (effective cost per thousand impressions) on any smartphone went to the iPhone, at $2.85 (£1.82). Android took second place, with an eCPM of $2.10, but the remaining devices proved to be far behind – with Windows Phone bringing up the rear with an eCPM of $0.20. The iPad, meanwhile, delivered an average eCPM of $3.96, which Opera attributes to its user-friendly design and large touchscreen.

Comparing each devices share of traffic and revenue on the platform, iOS emerges as the clear winner. Not only does iPhone lead the market in terms of traffic, with a share of 29.9 per cent, but also punches above its weight in revenue, making up 43.5 per cent of total revenue on the ad platform. The iPad does even better for itself, holding a revenue share (14.3 per cent) more than double its share of traffic (6.86 per cent).

Android again takes second place to iOS, with a roughly equal share of traffic (24.4 per cent) and revenue (26.6 per cent), and Windows Phone brings up the rear with less than 0.1 per cent of traffic. BlackBerry, meanwhile, holds a reasonable share of traffic (6.3 per cent) but a much lower share of revenue (1.8 per cent).

In terms of location, the majority of ad requests – a whopping 73 per cent – were driven by North America. eCPM is the highest in the US, at $1.98 – though the EU5 isnt far behind, with an eCPM of $1.94.