Year	PPP $ per kg of oil equivalent
1990	5.666471289127724
1991	5.782834289753968
1992	5.748009730734963
1993	5.518932216437297
1994	5.224075840995829
1995	6.560871642465628
1996	6.0759764580797535
1997	6.457913794757506
1998	6.445539339048554
1999	6.796294037820099
2000	6.914865399837942
2001	7.588311072071945
2002	7.951188701723458
2003	7.480036164044616
2004	8.647624263590185
2005	9.238818001870658
2006	9.764436085029585
2007	10.347340317104724
2008	10.605312309346905
2009	10.84153381442801
2010	11.377441258814747
2011	12.002647602632116
2012	12.3853841173797
2013	13.59445638049838
2014	13.036227756360049