Year	PPP $ per kg of oil equivalent
1990	2.3307726625885246
1991	2.8435200077174745
1992	2.8859333401550638
1993	2.714154286995811
1994	2.9109501486196834
1995	2.8171239084424684
1996	2.4935155431122484
1997	2.295966259759756
1998	2.546487732363886
1999	2.603636592359126
2000	2.820272975100445
2001	2.875119956319651
2002	3.292237260365204
2003	3.379923375647995
2004	3.7700791863375316
2005	3.961412788855448
2006	4.238585825886942
2007	4.809281858479352
2008	5.4160944206324615
2009	6.029999341969533
2010	6.188288017475747
2011	6.016725083090608
2012	6.495878435220735
2013	7.14797301393352
2014	7.1095879150115895