As Facebook filed for its initial public offer, it’s the perfect time to examine the website’s performance online and how its audience compares with that of other social networks.

Given the expected $75 billion to $100 billion initial valuation of Facebook, we’re all already aware of the magnitude of the business. Below we reveal how much of a behemoth the website itself is in the U.S. and other markets.

Facebook captures one in every eleven Internet visits in the U.S.

One in every five page views online occurs on Facebook.

The average visit time on Facebook is 20 minutes.

Facebook.com’s audience skews slightly more female than the online population as a whole.

The ages of Facebook ovisitors are indicative of the website’s strength in the marketplace, with relative parity in distribution of its visit share by age versus the overall online population.

Facebook under-indexes in visit share from the most affluent income group. With that said, Facebook’s size more than makes up the difference; the site wins 499,949,430 visits from the most affluent income group versus YouTube’s 223,732,591 visits and Twitter’s 15,166,795 visits.

Facebook became the number one ranked website in the U.S. on March 9, 2010.

“Facebook” is the most searched-for term in the U.S. and Facebook-related terms account for 14 percent of the top search clicks.

Facebook users are highly loyal to the website; 96 percent were returning visitors in January 2012.

Internationally, Facebook.com ranks in the top two websites in every market except China, where Sina Weibo, Baidu Zhidao and Renren are the dominant social networks.Facebook.com’s largest footprint is in Canada, capturing almost 12 percent of all visits in that market. It also recently surpassed Orkut, placing it behind only Google Brazil in market share.

Facebook is the largest website in the U.S. and a top performer in numerous international markets.

The fan base of the site is loyal and spends a significant portion of their time online on the social network. Facebook’s influence is seen in the presidential elections, digital shopping habits and beyond.

Guest writer Heather Dougherty is research director at Hitwise North America.