It was followed by France on 35.7%, the Netherlands on 35.1%, Sweden on 31.3% and Denmark on 31.2%.
For the report, the media agency identified the top 19 digital markets across the world and then examined how consumers in them use digital media, how internet advertising, social media and e-commerce are developing, and how quickly new media technologies are being adopted.
Canada was the leading North American country, in 6th place on 30.5%, while Australia, on 24.6% was the top APAC country. Brazil led the way for Latin America in 17th spot on 11.2%.
By 2015, Western European countries are expected to continue to dominate the leading positions on the rankings, Zenith said. The Netherlands is forecast to take the top position, on 65.1% penetration, with the widespread uptake of IPTV the main driver with forecast Dutch penetration of 90%.
France (60.8%) and Norway (48.2%) will be joined by Ireland (50.2%), where half the population is predicted to have access to tablets, helped by government investment in providing tablets to schools. This is not only increasing their availability but is also encouraging sales to parents keen to understand their advantages.
Canada, in fifth spot with 47.7% penetration, will continue to be the top North American country, Australia the leading APAC country on 40.9%, while in Latin America, Brazil more than doubles to 26.9%.
Smartphones are by far the most widespread of the three technologies considered for the Zenith report, with an average 35.5% penetration across the 19 nations in 2012. Comparable figures for tablets and IPTV are forecast to stand at 4.7% and 6.6% respectively.
And while there are huge variations in smartphone penetration – 73% in Sweden, for example, compared to just 18% in Brazil – the overall figure for the 19 countries is forecast to double to 71.7% by 2015.
Tablets are expected to increase fastest over the next three years, with penetration rising 177% to 13% in 2015. IPTV will grow more slowly at 36% to reach 9%.