Analyzing 35 million citations from 7,000 journals, researchers at the University of Washington and the Santa Fe Institute have traced and plotted changes and fluctuations in the prevalence of various fields of scientific study over the past decade.
Among the most notable observations are the branching of broad study areas into more specialized, standalone disciplines, and the emergence of newly defined fields, such as neuroscience (which was, indeed, an interdisciplinary concentration when I majored in it — or something like it — as an undergraduate in the nascent millennium):
The alluvial diagram illustrates, for example, how over the years 2001–2005, urology gradually splits off from oncology and how the field of infectious diseases becomes a unique discipline, instead of a subset of medicine, in 2003. But these changes are just two of many over this period. In the same diagram, we also highlight the biggest structural change in scientific citation patterns over the past decade: the transformation of neuroscience from interdisciplinary specialty to a mature and stand-alone discipline, comparable to physics or chemistry, economics or law, molecular biology or medicine.
Also worth remarking: the conspicuous lack of progress in the field of making graphs that don’t give you a migraine.
No Happy Medium 
Much more useful: http://www.xkcd.com/657/