Year	PPP $ per kg of oil equivalent
1990	7.114186600831897
1991	7.292787193345515
1992	7.3418487735174836
1993	7.693478364622488
1994	7.900980310660861
1995	8.129096234619997
1996	8.03348110751589
1997	8.041225980254291
1998	7.967940371788363
1999	7.938569581541534
2000	8.440677374676131
2001	8.600643174971399
2002	8.768936396762582
2003	8.89781724528225
2004	9.154302607644368
2005	9.504281482798598
2006	9.843363364564443
2007	10.147934834992663
2008	10.296640866835054
2009	10.696788485834
2010	10.528629929007927
2011	11.000725975589061
2012	10.620251690132774
2013	10.623885224384669
2014	10.44319047513363