Ebook sales grew 54% in 2011
"Digital content now accounts for 8% of the total value of book sales in 2011 - it made up 5% in 2010."
Book sales overall were down though due to a 5% drop in physical book sales.
Still, good news for the indies if ebooks are on the rise, though it may mean more competition from the big publishers if decide to start taking ebooks more seriously.
Still, 8%, plenty more room for growth!