Textbook costs continue to rise faster than overall college costs. The Bureau of Labor Statistics reports
From January 2006 to July 2016, the Consumer Price Index for college tuition and fees increased 63 percent, compared with an increase of 21 percent for all items. Over that period, consumer prices for college textbooks increased 88 percent and housing at school (excluding board) increased 51 percent.
The student cost for an Open Educational Resources textbook? $0
An interactive graph is available at http://www.bls.gov/opub/ted/2016/college-tuition-and-fees-increase-63-percent-since-january-2006.htm