Academic researchers generally want their papers to be read by as many people as possible. But the journals that publish those papers are, in many cases, for-profit institutions — and they prefer charging for access.
Lately, however, the Open Access movement has been fighting to make more and more research free to the public. And they're succeeding. Here's a snapshot of what was freely available to the public in 2010, sorted by discipline:
The big black line shows the percentage of papers in all subjects published between 1998 and 2006 that was freely available. But there's also great variation between different types of research. Topping the open list are mathematics, social sciences, and Earth sciences — each has 30 percent or more of its 2006 papers free. But compare that to clinical medicine, which is less than 5 percent.
Some of this variation is because of different research cultures. For example, many physicists have been posting pre-publication manuscripts on a public website called arXiv since 1991, so it's not a surprise that physics (designated by blue crosses on the chart) also tends to have more of its peer-reviewed papers freely available.
By contrast, clinical medicine and biomedical papers were some of the least likely to be freely available — at least when this chart was made. One possible reason why? Many medical institutions are willing to pay big bucks for access.
It's worth noting that even that is changing, however. In 2008, the National Institutes of Health began requiring papers generated by the research it funded (which is taxpayer money) to be freely available to the public a year after publication or earlier. That's opened up a large chunk of biomedical research.
The chart comes from a 2012 UNESCO report on the practice of open access, which the organization strongly encourages as a way to spread knowledge and information worldwide:
Through Open Access, researchers and students from around the world gain increased access to knowledge, publications receive greater visibility and readership, and the potential impact of research is heightened. Increased access to, and sharing of knowledge leads to opportunities for equitable economic and social development, intercultural dialogue, and has the potential to spark innovation.