Researchers estimate that by the end of 2011 one third of all
scientific articles will be available for free online via OA
platforms. Two main forms of OA have evolved: Green OA, on the one
hand, where the author simply makes papers available in repository
online archives; on the other hand, Gold OA where the author pays a
professional agency to properly publish articles online together
with peer reviews.
Boom of Green and Gold OA
Current star of the OA community is PLoS
One, the largest peer-reviewed online journal in the world.
This year, PLoS One expects to publish around 11.000 articles
available for free on their website. The OA phenomenon has drawn
considerable attention from researchers and publishers worldwide
aiming at quantifying its success.
Bo-Christer Björk from the Hanken School of Economics in Finland
estimated that in 2009 Gold OA publishing had a market share of
7,7% growing at an annual rate of 0,5%. His research showed that
since 2000 the number of Gold OA journals grew on average at 18%
per year with 30% yearly growth in the number of scientific OA
articles.
Yassine Gargouri, postdoctoral researcher at Université du
Québec à Montréal (UQAM), conducted research into the field of
Green OA and found that in 2010 its market share was around 21%.
Bringing these findings together almost 30% of all scientific
articles are available for free online with Gold OA representing
1/3 and Green OA 2/3.
Doubts from Established Publishers
Meanwhile, Derk Haank, CEO of the well established publisher
Springer, remains critical of the current trend in OA. He doubts
the OA market share estimates and states that he "expects [them] to
remain between 5% and 10% at a maximum." These doubts may be well
justified in some cases. Especially for Green OA, numbers can be
often deceptive as it is difficult to distinguish complete
scientific articles from short incomplete excerpts in online
archives.
Advocates of OA see these growth numbers even more critical with
a slightly different angle. Stevan Harnad, cognition researcher at
the British University of Southampton, says that "these growth
rates are portrayed as dramatic, but they are not dramatic at all
if the goal is 100% open access." For the sake of knowledge sharing
and Isaac Newton's 'standing-on-shoulders-of-giants' OA has to grow
much more and faster.

Source: M. Laakso et al. PLoS ONE 6, e20961 (2011)