American internet users are spending increasing amount of time on social networking sites such as Facebook, Twitter and YouTube, while the amount of time spent on e-mail and traditional web portals have declined,according to a recent research report from Nielsen.

The result of the study says that web users, in June, devoted 23% of their online time to social networking sites, up from 16% a year ago. Online games ranked second, previously held by e-mail use, where people spend 10% of their time, powered by social games like Zynga’s Farmville.

Another major service to enjoy increase user time in June was streaming of videos and movies  with 3.9%, up from 3.5% a year ago.

This is no major surprise as Facebook, Twitter and YouTube together enjoys close to one billion users, or roughly 20 percent of the world’s population.

Time spent on E-mail dropped from 12% to 8.3%, while online time spent on traditional portals like Yahoo! also fell from 5.5% to4.4% in the last one year.

“You can start your daily online experience on Facebook and perform many essential communications functions,” Nielsen analyst Dave Martin said. “In the past, you might have to log into Yahoo Mail and then log into MSN Messenger and then maybe check the Yahoo home page for new, breaking news.”

Another interesting detail the report showed was; twice as many users over the age of 50 are using social networks than users under age 18, indicating the social network audience is getting more matured.

How much time do you spend on social networking sites like Facebook and Twitter. The answer will differ from person to person, but can you guess how much time an average user spend tweeting and facebooking?

According to a survey by The Nielsen Company, the average social network user around the world spend more than five and a half hours on sites like Facebook and Twitter in December 2009. This is an 82 percent jump from December 2008 when Tweeters and Facebookers spend around three hours the entire month.

Social Networks and blogs proved to be the most popular sites in December. Facebook was the top social-networking site in December with 67% of social networking users around the world.

Among all countries, the United States led the way with the largest number of people checking out social-networking sites at 142.1 million unique visitors.

Australian users top the list of most time spend at social-networking sites with almost seven hours for the month, while U.S., U.K., and Italy users spent around six hours.

Although, Japan came in the number of unique visitors with 46.5 million users after the United States, it had a much lesser average usage time of around 3 hours.