Looking at the top ten in minutes per viewer... the Google Sites lead was astonishing, with 500.1 min/viewer in June.
Follow ups in #2 and #3 positions were...
- NDN (News Delivery Network), with 86.6 min/viewer
- Yahoo Sites, with 73.6 min/viewer
Facebook appears to be #9 on the list of the top 10, with 24.7 min/viewer, and Amazon Sites #10 with 19/1 min/viewer.
What's not clear to me is how shared views are counted... eg, whether a YouTube video viewed on Facebook is attributed to YouTube or to Facebook.