This photo of First Lady Michelle Obama (L) and US President Barack Obama (R) hugging after delivering remarks during a campaign event at the Alliant Energy Amphitheater in Dubuque, Iowa, August 15, 2012, became the most re-tweeted image in the network’s history. (JIM WATSON/AFP/GETTY IMAGES)

Twitter let loose Tuesday with its list of the top trending topics for 2012.

Slicing its massive store of data several ways, the company has highlighted the most popular single tweets, trends across a number of topics and the biggest conversations of the year.

The most retweeted message of the year — and in the history of the network — came from President Obama, whose message “Four more years” accompanied by a picture of the first couple garnered 810,000 retweets. The second most-shared message came from Justin Bieber, who occupies the highest echelon of the Twitterati, as he mourned the loss of six-year-old fan Avalanna Routh to brain cancer.

Twitter’s list of top conversations closely mirrors the lists already released by Bing and Yahoo, though with a few outliers. The Summer Olympics generated 150 million Tweets, spiking with 116,000 tweets per minute during the closing ceremonies. Usain Bolt gained the distinction of being the games’ most-discussed athlete.

The U.S. election produced more than 31 million tweets on Election Day, and 10 million during the first presidential debate alone. The MTV Video Music Awards, Super Bowl, Euro 2012, Hurricane Sandy, UEFA Champions League Semi-Final and the death of Whitney Houston were also subjects of debate.

A couple of interesting trends popped up on Twitter’s list that weren’t on the other trend lists, highlighting some of the differences between social and search.

Social networks, of course, are more focused on creation and sharing content than finding it. They also tend to highlight Web-centric communities. For example, a Japanese show called “Summer Wars” edged onto the list of top conversations thanks to an impromptu real-time event organized by fans who sent the same line from the show at the same time. The debate over the Stop Online Piracy Act and Protect IP (Intellectual Property) Act also made the list, as Twitter was an important center of that debate.

The company also highlighted some of its newest celebrity members ranging from Steve Carell and Neil Young to Pope Benedict XVI.

Users interested in getting an analysis of their own year on Twitter can do so via the company’s “Your year on Twitter tool,” which ships data from individual accounts to the personal Web site company Vizify. Once there, signed-in users can see a pattern of their own tweets throughout the year and track which of their messages were the most popular.

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