Mobile is a fast-growing trend for marketers, thanks to various types of advertising being available, allowing for a better outreach to consumers. In 2015, however, those numbers are sure to rise even more.

A new report from ZenithOptimedia indicates that mobile advertising spending has already grown at an exponential rate for this year, six times faster than desktop advertising worldwide, according to Mobile Marketing Magazine. This includes classified, search and display ads that are included in both in-app advertising and on mobile browsers.

Furthermore, the report shows that the growth is expected to be around 38.3 percent over the next three years, leading into 2017. Meanwhile, desktop is only slated to grow an estimated 6.7 percent — just a fifth of mobile’s growth.

Overall mobile spending is estimated to reach over $25 billion for this year alone, and will increase to an even higher amount by 2017 — nearly triple the value at $68.2 billion. That calculates to around 11.3 percent of total spending.

With that, the market share for new ad dollars is estimated to reach 51 percent of extra spending, according to Zenith, over the next three years. That calculates to an additional $42.4 overall. By comparison, desktop comes up a little shorter, up 25 percent to a total of $20.6 billion.

Meanwhile, out of those mobile markets, Facebook and Twitter will account for a pretty big chunk. An estimated 33 percent of mobile ad spending will be done through those networks for this year, compared to 10 percent for digital sharing overall. These numbers could pick up over the next few years, and other social networks could get involved as well.

Meanwhile, eMarketer had its own numbers to report, indicating that more paid search ads and SEO efforts would be invested in via mobile starting next year. It estimates that 76.7 percent of US search spending will go to mobile within just four years’ time, by 2018. That’s a huge leap from the 24.7 percent of spending that went into mobile last year.

However, ROI on mobile, which continues to rise, isn’t quite on the same pace and is likely to fall behind desktop spending over the next year. eMarketer believes that an increase in tracking and attribution could certainly help marketers along with better grasping it.