Around 694 million adults across the globe use the internet - according to a new survey by market researcher comScore Networks.
The US-headquartered company's World Metrix survey claims to standardize global online measurements and will provide monthly figures for internet usage among people aged over 15.
The numbers for March estimate US users at 152 million, or 22% of the worldwide total. China's, Japan's, India's and Korea's users together number 168.1m, or 25% of the total.
Comments Peter Daboll, ceo of comScore Media Matrix: "Today, the online audience in the US represents less than a quarter of internet users across the globe, versus ten years ago when it accounted for two-thirds."
He adds: "This is a sea change of enormous proportions."
In Europe, Germany notched up the highest number of internet users in March, with 31.8m, closely followed by the UK's 30.1m.
The study found that among major web sites, search leader Google and close rival Yahoo were neck and neck in terms of total worldwide audiences.
But it was Microsoft's collection of sites which attracted the largest global audience with 538.6m. This includes its consumer internet audience for MSN, instant messaging and Hotmail and also traffic to Microsoft.com for software downloads and other non-consumer activities.
Data sourced from MrWeb.com; additional content by WARC staff