so the top 5 sellers of the year are (so far):
STIUTK ~ 6.2-6.3M
CMM ~ 5.3M
WAY ~ 5.2-5.3M
Payphone ~ 4M
Stronger (??) ~ 3.6-3.8M
EDIT: SFTTR should be in there somewhere, but for year-end songs, Billboard only counts from December 1 through Nov 30, and I believe it was already selling well way before December.
The song reached the 4 million mark in just 19 weeks. Only one song in digital history has reached 4M faster. "E.T." by Katy Perry featuring Kanye West was in its 18th week on Hot Digital Songs when it topped 4 million.
