Search ad spending will surpass $80bn (£54bn) this year, up 16.2 per cent year on year, and representing almost half of the $170.85bn set to be spent on digital ads worldwide in 2015.

Research by eMarketer suggests that while the rate of growth is beginning to slow for search ad spending, it will remain in double figures until 2018, and will total $130.58bn in 2019.

Google remains the dominant player in search ads, and while its market share has dipped slightly year-on-year, it has seen growth of 15.7 per cent, taking its total expected search ad revenue to $44.46bn, over half of the search ad spending globally.

Baidu, Chinas largest search advertisers, held second place, with an 8.8 per cent market share, and revenues up 34.2 per cent year on year to $7.18bn. The companys growth is a testament to the increasing influence of China on the global scale, with search ad spending in China reaching $14.9bn this year, accounting for 18.2 per cent of the market and up 32.8 per cent on 2014.

Microsoft and Yahoo held on to third and fourth places respectively, with market shares of 4.2 per cent and 2.3 per cent. While both saw growth, Microsofts has dramatically slowed over the past three years, dropping from 48.7 per cent to 18.5 per cent. Yahoos growth, while lower, reversed the drop it saw last year, with growth increasing to 6.9 per cent from 4.8 per cent.