Sharing widget AddThis, which is installed on more than 7 million domains and reaches more than one billion users per month, released an infographic Wednesday with some interesting statistics about about our sharing habits. Impressively, 44% of shares occurred through Facebook in 2010, up 33% from last year. That number does not include shares done via Facebook’s “Like” button, which means the actual, universal percentage of shares through Facebook is likely higher. Shares over Gmail increased by 395%, outpacing StumbleUpon, Facebook and Twitter. Shares via MySpace and Friendster dropped 20% and 31% respectively.