Tumblr may not be a popular player on the world stage, but data from a new comScore study [download page] shows that it’s heavily used by Americans, relative to other popular sites. Analyzing share of time spent on social networking sites in December 2012, comScore reveals that while Facebook dominated at 83% share, Tumblr occupied the second spot 5.7%, more than Pinterest 1.9%, Twitter 1.7%, and LinkedIn 1.4% combined, and almost as much as the aggregate of all other social networks 6.1%.

via Tumblr Beat Pinterest, Twitter, and LinkedIn for SocNet Time Spent in December.