Swan & Brown (2004)  (2005)

"asked authors to say how they would feel if their employer or funding body required them to deposit copies of their published articles in... repositories. The vast majority... [81%] said they would do so willingly."

Swan, A. & Brown, S.N. (2004) JISC/OSI Journal Authors Survey Report. http://cogprints.org/4125/

Swan, A. & Brown, S.N. (2004) Authors and open access publishing. Learned Publishing 2004:17(3) 219-224. http://cogprints.org/4123/

Swan, Alma and Brown, Sheridan (2005) Open access self-archiving: An author study. Technical Report, Joint Information Systems Committee (JISC), UK FE and HE funding councils. http://cogprints.org/4385/
Harnad, S., Brody, T., Vallieres, F., Carr, L., Hitchcock, S., Gingras, Y, Oppenheim, C., Stamerjohanns, H., & Hilf, E. (2004)
The Access/Impact Problem and the Green and Gold Roads to Open Access. Serials review 30(4). http://eprints.ecs.soton.ac.uk/10209/

Harnad, S. & Brody, T. (2004) Comparing the Impact of Open Access (OA) vs. Non-OA Articles in the Same Journals, D-Lib Magazine 10 (6) June http://www.dlib.org/dlib/june04/harnad/06harnad.html

Current status quo for Open Access Provision


Estimates for baseline self-archiving percentage of 15-20% confirmed at: 
http://citebase.eprints.org/isi_study and

Current Potential for Immediate Open Access Provision
(note that 49% of authors in 2005 have now self-archived at least once and
that the 2004 percentage who say they will self-archive willingly if required
has since risen, in a second, larger S & B survey in 2005 from 69% - 81%)