From the Association of Research Library:
Many ARL member libraries and industry experts seek inflation-adjusted ARL library expenditures data. Now these data are available in an interactive graphical interface thanks to the work of Steve Batt, associate director of the Connecticut State Data Center—a collaboration between the University of Connecticut (UConn) Libraries, the UConn Department of Geography, and the State of Connecticut Office of Policy and Management.
You can access and customize the graphs for “Inflation-adjusted expenditures for individual ARL libraries, 1987–2014” in addition to the “Median library expenditures among ARL libraries, 1963–2014” and “Percent change in expenditures, 1987–2014.” Batt used data from the annual ARL Statistics publication and the ARL Statistics Analytics along with Tableau data-visualization software to create these interactive graphs.
Batt’s Tableau Public page includes many more data-visualization stories, including a series of interactive graphs from the US National Center for Education Statistics Academic Libraries Survey 2012 and from the ARL Library Investment Index 2003–2014, an annual summary measure of the relative size of the university library members of the Association of Research Libraries.