Publishers Weekly shared some Nielson BookScan data showing that sales of print books fell by 10.2% in the first half of 2011, with sales of mass market paperbacks falling the fastest at 26.6%. This time last year, it was the same song except that print sales were down only 0.4% in the first half of 2010, with sales of mass market falling the fastest at “only” 4.6%.

An acceleration from .4% to 10.2% and 4.6% to 26.6%, in only a year’s time, is a crazy thing to wrap my mind around. I hope everyone in ANY kind of publishing is cranking out new ideas to respond to what and how readers want to read.

Also, I should mention that BookScan covers about 75% of the shops out there and they do not yet track ebook sales. So any comparison or shift in consumer behavior is guessing based on their data.