Year	constant 2021 PPP $ per kg of oil equivalent
1990	20.630047669687578
1991	19.88307356280307
1992	16.816411403960096
1993	17.65014274344171
1994	18.7241149078566
1995	19.1113621403968
1996	19.287396522662856
1997	20.088408785465855
1998	21.650335577034284
1999	20.46082821041745
2000	19.44175730038215
2001	20.001000718750166
2002	19.66108275577781
2003	19.109036587850806
2004	16.843717044564137
2005	17.519311810590317
2006	17.377971902862768
2007	17.446847832878614
2008	17.965074062138388
2009	17.905582726971588
2010	18.51945899891807
2011	19.297945847980074
2012	19.909385987278075
2013	19.94006553069633
2014	20.382075869642925