In May 2012, WebAIM conducted a survey of preferences of screen reader users. We received 1782 valid responses to this survey. This was a follow-up survey to the original WebAIM Screen Reader User Survey of January 2009 and the follow-up surveys from October 2009 and December 2010.

Read more at
http://webaim.org/projects/screenreadersurvey4/?goback=%2Egde_2484780_member_120522872