In another post, I mentioned searching the Internet for the latest numbers on eBooks and audiobooks. I found two articles in Publishers Weekly that gave me the answers I wanted.
According to a September 25 article, the estimated spending on audiobooks in 2004 was $832 million. The estimated spending on audiobooks in 2005 was $871 million. That's a increase of 4.6% from 2004 to 2005.
While the spending on audiobooks was more than four times as large as the spending on eBooks, the growth in spending on eBooks was almost ten times that of audiobooks from 2004 to 2005.
Other interesting facts:
24.6% of adults have listened to an audiobook in the last year. The average household income of audiobook listeners was $57,000.
63% of the audiobooks were purchased in bricks and mortar stores while 31% were bought online and 6% were purchased by phone or mail order.