Google and Facebook together took 20 percent of the world's advertising budget across all media in 2016, according to a report published today. The figure has grown by nine percentage points in five years.

Media agency Zenith's Top 30 Global Media Owners report lists Google's parent company Alphabet at number one, taking $79.4 billion, followed by Facebook, which earned $26.9 billion in advertising revenue.

Comcast takes third place, with $12.9 billion, making it the largest traditional media owner.

U.S. companies dominate the media ranking, Zenith said, because the country has the world's largest ad market. Businesses also invest in overseas expansion, while Silicon Valley tech powers internet advertising, it added. American companies on the list also include The Walt Disney Company, Viacom, iHeartMedia and Verizon, which owns AOL and is in the process of acquiring Yahoo.