Screen readers - usage stats?

When writing and testing HTML, it's standard practice to test with
multiple browsers and multiple versions of those browsers. It's also
pretty standard to look at usage stats for those browsers - how many
people are still using IE 4.0 or Netscape 4.7? Such statistics are often
unreliable, but they're still worth considering, especially if pulled
from your own server logs.

What about screen readers? Is there any available information on usage
of various screen readers, and specifically on version? Obviously
statistics in this case would be difficult to compile, since you can't
simply pull the information from server logs. But it would be valuable.

As an example: for a particular upcoming project, tagged PDF files are
being considered as the primary document format. When discussing the
need, if any, for alternative versions, it would be helpful to know how
many users of screen readers would be able to read a tagged PDF file,
and how many are using software that can't handle that format.

Please note: I'm not asking for opinions on the need for alternative
versions - this is just an example of one situation in which having
statistics would be valuable. 

Any pointers to any real numbers would be greatly appreciated.

Received on Wednesday, 14 April 2004 13:39:41 UTC