Amidst news of a Netflix site outage this afternoon, a new report says Netflix accounts for more than 20 percent of all downstream Internet traffic during peak times in the U.S.

U.S. Netflix streaming traffic is heaviest between 8-10pm.

"For service providers, this is a double-whammy: not only are they losing revenue to these over-the-top offerings, but they are losing network capacity delivering these services," according to the report, produced by Sandvine.

The finding underscores the growing popularity of free video and audio streaming sites, like Hulu and YouTube, at the expense of peer-to-peer sites, like BitTorrent. According to the report, these "real-time communications" portals represented 42.7 percent of North America's Internet traffic this year, up from 29.5 percent in 2009.

In North America, the average time a person's Internet connection is active is three hours, whereas in Asia-Pacific, it's closer to 5.5 hours, Sandvine said.

In September, Netflix expanded into Canada with a streaming-only service, and the company said Wednesday that it is considering a streaming-only option in the U.S. for the fourth quarter. Profits climbed 26 percent year-on-year this quarter, according to a recent earnings report.

Sandvine's 'Fall 2010 Internet Phenomena' report is based on voluntary survey results from over 300 million Sandvine subscribers around the world. It examined traffic data from North America, Latin America, Europe, and Asia-Pacific.

Sandvine was last in the news during the Comcast vs. FCC network management debate. Comcast reportedly used Sandvine technology to throttle peer-to-peer traffic on its network - in particular BitTorrent. Consumer groups and former FCC Chairman Kevin Martin accused Comcast of using Sandvine technology, but Comcast has never admitted to doing so.