Year	PPP $ per kg of oil equivalent
1990	1.3511188173640638
1991	1.3385931871223977
1992	1.2811354318730268
1993	1.268717099680459
1994	1.295426185838942
1995	1.308245552813044
1996	1.2975224132125223
1997	1.400586140377971
1998	1.3726126061938433
1999	1.429703130908945
2000	1.6157536997281992
2001	1.7165827565491636
2002	1.8743263047311765
2003	2.0744012204831535
2004	2.275807296900168
2005	2.6035203803313527
2006	3.180671974465793
2007	3.5347749320323048
2008	4.180610134945018
2009	4.279124998126588
2010	4.251909798178427
2011	4.5151016332921055
2012	4.703585197895097
2013	5.134040738055008
2014	5.294171484989187