Over 2/3 of Mylo Xyloto's US first week sales were downloads

"Coldplay has already pulled impressive, first-week album sales stats. But now, it looks like a monstrously large percentage of those sales were in the form of digital albums, particularly in the US.  We just received a complete first-week breakdown on Coldplay's Mylo Xyloto, and it shows that out of 447,411 total albums sold, more than 300,000 were digital.  Or, more precisely, 302,183, or 67.5% of total, according to first-week album sales tallied by Nielsen Soundscan."
Source:  Digital Music News, 3rd November 2011