Year	constant 2011 PPP $ per kg of oil equivalent
1990	10.712150114831
1991	10.798973886908
1992	10.7339025097268
1993	11.1924487624714
1994	11.049485623374
1995	10.9518254032462
1996	10.9702907430228
1997	10.9416777844118
1998	10.5639244581059
1999	9.98691454485776
2000	10.0455975782309
2001	10.0688887140381
2002	10.3742399977885
2003	10.2322572359047
2004	10.2484908206144
2005	10.5259389945691
2006	10.9214443637931
2007	10.8054190441055
2008	11.6447262898799
2009	10.1982769422842
2010	9.63562088252211
2011	9.38696021375844
2012	9.51528258830376
2013	9.07032352501708
2014	8.61037038290519