Stats released by internet traffic research company Hitwise have raised doubts over the success of Web 2.0 sites such as YouTube, Flickr and Wikipedia. 

Speaking at the Web 2.0 Expo in San Francisco on Tuesday, Bill Tancer, general manager of Hitwise, said that the company's data showed that only a tiny fraction of users contributed content to community media sites.

Just 0.16 per cent of YouTube users upload videos, and only 0.2 per cent of Flickr users upload photos.

Wikipedia returned a more reasonable percentage, with 4.6 per cent of visitors actually editing and adding information.

The figures show that, while users are flocking to these sites in droves, the vast majority only passively absorb the content, rather than actively participate, which is considered by many to be a vital part of the Web 2.0 model.

However, these tiny percentages are offset by the massive growth in traffic to 'participatory' sites which has increased from two per cent of all internet traffic in 2005 to 12 per cent today, equating to a 668 per cent increase.

"One of the questions I am asked most often is if Web 2.0 is just a fad or if it will get traction," said Tancer. "Web 2.0 and participatory sites [are] really gaining traction."

Recent research by analyst firm In-Stat has concluded that the user generated content market is still in a rapid state of flux, due largely to the high profile lawsuits, acquisitions and experimentation. 

Business models continue to adapt and change, as do experiments with advertising, making the overall landscape appear to be as dynamic as a feather in the wind.

The research also indicates that worldwide revenue from user generated content will increase from $80m in 2006 to $1.6bn by 2011.

As more content is viewed on TV rather than the computer monitor, the impetus to submit and receive higher quality content will translate to much larger files being uploaded and downloaded.

Barry Parr, an analyst at Jupiter Research, said: "I did not realize that Flickr was having a problem getting people to upload photos. 

"Consumer created content is now the big leagues, but we still don't understand it all that well. It's a reasonable (and old school) rule of thumb that only one per cent of any site's readers will post content on it, but that's plenty.

"That's consistent with the Flickr number from Hitwise, if the posters are uploading once every five visits."

Ted Shelton, vice president of business development at Technorati, argued that a small percentage of a huge number of users can still amount to a significant impact. 

"Two per cent of a billion people online is still 20 million people writing blogs on a regular basis," he said.

"Very few of those 20 million people actually worry about getting paid for what they do. People under 25 are much more likely to blog, and contribute content of other kinds, so this may be a phenomenon that is increasing."