Year	PPP $ per kg of oil equivalent
1990	2.2845083212398056
1991	2.2418067034184945
1992	2.4089018430016247
1993	2.497757337843152
1994	2.8184177569980253
1995	2.979631398749359
1996	3.0876395489565835
1997	3.3804617984078082
1998	3.857042142726935
1999	4.1894819432881185
2000	4.5998900213670755
2001	4.760650444954465
2002	5.100792110470277
2003	5.17436302700219
2004	5.603755575164709
2005	5.756363736859446
2006	5.972557010870175
2007	6.649756468466571
2008	7.1364343231646385
2009	7.800196683177575
2010	7.911105802317761
2011	8.539363117368215
2012	9.190907683200777
2013	9.478957143942925
2014	10.235409189740313
2015	10.77126138716318