AddThis is a widely used social bookmarking service. They've recently published an infographic with some of the most striking trends in sharing over 2011.
Timeline of the most shared events in 2011
- Facebook makes up 52.1% of sharing on the web
- Twitter makes up 13.5% of sharing (still less than email, print and favorites) but grows 576.9%. In Japan, Twitter makes up 52% of sharing.
- Tumblr sharing grows by 1299.5% and is accelerating
- Address bar sharing creates 1600% viral lift.