As kids increasingly shift from TV to online, more than 40% of total new internet users globally in 2018 were children—the fastest growing segment of online audience. These kids are also a powerful demo for the advertising market, according to new research from research firm PwC, commissioned by UK-based digital kids company SuperAwesome.

The 2019 Kids Digital Media Report estimates that the global kids digital advertising market will grow by more than 20% per year between 2018 and 2021, making it worth US$1.7 billion by 2021. This is the first time PwC has revisited this research since its 2017 report that estimated the market would reached US$1.2 billion by 2019, with digital spending reaching 28% of total kid-focused advertising spend in the sector. (The report doesn’t specify whether these predictions came true.)

The two companies found that each day, more than 170,000 children head online for the first time, and kids media and content is increasingly consumed via desktop, mobile and tablet devices. As such, PwC says it expects brands will be moving more advertising spend onto these platforms and shifting away from traditional (non-digital platforms) in the next few years.

But despite all of this growth, a significant amount of content investment is going into subscription services which rarely carry advertisements, making them unreachable for brands.

The report is generated by proprietary interviews with a range of companies in the kids digital media space, including brands, agencies and specialist agencies.