Pew Internet & American Life Project. April 13, 2012.
While the number of Americans who go online has increased substantially over the years, about one-in-five adults still do not use the internet. About half of non-users don’t go online because they don’t think the internet is relevant to them. Moreover, the 27% of adults living with disability in the U.S. today are significantly less likely than adults without a disability to go online. [Note: contains copyrighted material].
http://www.pewinternet.org/~/media//Files/Reports/2012/PIP_Digital_differences_041312.pdf [PDF format, 41 pages].