Year	constant 2021 PPP $ per kg of oil equivalent
1990	12.563236080729181
1991	12.589905299413513
1992	12.65840866071289
1993	13.02264246523337
1994	13.14477297590065
1995	13.021975889568326
1996	12.983076157933422
1997	13.10711460734431
1998	13.074253215962381
1999	12.878491688237665
2000	13.174194890157858
2001	13.067030831218535
2002	12.978383507697753
2003	12.847270272991176
2004	13.00635473681742
2005	12.974230627797027
2006	13.129960313819511
2007	13.45863955158194
2008	13.619482828218487
2009	13.433916890944683
2010	13.671180516661353
2011	13.871024055403534
2012	13.72959735164735
2013	13.76464463655848
2014	13.722439672272905