By Daniel Hunter

The amount spent by businesses advertising on social media has more than doubled over the past year, according to marketing software firm Kenshoo.

Quarterly global spend on social advertising grew by 114% year-on-year in Q2 2015, twice as fast as a year ago.

Mobile phone and tablet ad spend is up 167% compared with the same period last year and together they now account for 63% of total paid social budgets (up from 51% last year).

The data highlights key quarterly metrics and benchmarks for paid search and social advertising based on 550 billion impressions, 9.5 billion clicks and $5.5 billion in advertiser spend through the Kenshoo Infinity Suite.

In paid search, the research reveals that quarterly spend increased by 10%, fueled entirely by growth in mobile ads (71%) and tablet ads (4%), while desktop search spend decreased slightly (-2%). Mobile devices are playing an increasingly bigger role in search advertising, accounting for 38% of spend (a 37% rise), 44% of clicks, and 34% of advertiser revenue.

“Both paid search and social are showing healthy increases in spend and clicks with social obviously showing the much faster growth as it’s a far younger market,” said Rob Coyne, Kenshoo’s Managing Director for EMEA.

“Existing social advertisers are ramping up spend and getting better results in terms of click volumes despite fewer available impressions, while new social advertisers are also entering the market. Mobile has been the key driver of growth in both search and social, with 36% of revenue from advertiser sales now coming from mobile phones, up from 16% last year.”

Total clicks from social advertising increased by 129% over the year on top of 64% fewer impressions, demonstrating that marketers are becoming more savvy at driving clicks on (and engagement with) social ads. Social advertisers have also enjoyed a dramatic 535% rise in click-through rate (CTR) as they adjust, adapt and take advantage of changes in the structure and available inventory of paid social publishers.