The Open Science and Research Initiative has released "Transparency and Openness to Scientific Publishing: The Finnish Research Organisations Pay Millions of Euros Annually to the Large Publishers."
Here's an excerpt:
Open Science and Research Initiative announces the scientific publisher costs paid by Finnish universities and research organizations from 2010 to 2015. According to the data, the publisher costs have risen around ten percent per year. . . .
Publisher cost data is now available as open data licensed under CC BY 4.0 license. You are free to share and adapt the data for any purpose, with author attribution and indication if changes were made. Publisher cost details and a link to the web application can be found at openscience.fi/publisher_costs.