Time has its "Person of the Year." Amazon has its books of the year. Pretty Much Amazing has its mixtapes of the year. Buzzfeed has its insane-stories-from-Florida of the year. And Wonkblog, of course, has its graphs of the year. For 2013, we asked some of the year's most interesting, important and influential thinkers to name their favorite graph of the year — and why they chose it. Here's Vaclav Smil's.

"[There are] too many choices possible, but here is one epoch-making trend: as the post-2008 rise of hydraulic fracturing drove U.S. natural gas prices down and increased the supply (in 2013 the U.S. will be again the world’s largest natural gas producer) oil and gas prices, traditionally moving in tandem, have diverged significantly. History is being made."

Vaclav Smil is a Czech-Canadian scientist and policy analyst. He is Distinguished Professor Emeritus in the Faculty of Environment at the University of Manitoba in Winnipeg, Canada.

See all the graphs of 2013 here, including entries from Bill Gates, Jonathan FranzenPatty MurrayTyler Cowen, Bill McKibbenEmily OsterTa-Nehisi CoatesBrian Greene, Anne-Marie SlaughterChuck Schumer,  Chris Hayes, and Ron Wyden.