Year	PPP $ per kg of oil equivalent
1990	6.601728827752311
1991	6.731447786814935
1992	6.446940716273751
1993	4.844149359014405
1994	4.946227245344872
1995	5.812066197323924
1996	6.530613239755947
1997	6.974587119678132
1998	7.40251449626652
1999	7.303241157360652
2000	7.493046457641297
2001	7.647524393254369
2002	8.438005804998781
2003	8.21235878663467
2004	9.09421543259605
2005	11.164328883106398
2006	11.700839758729671
2007	12.845237706715901
2008	13.446752507066659
2009	12.556742798049726
2010	12.64898950703039
2011	12.861247431366065
2012	13.352238500542464
2013	14.247177083527307
2014	14.790825680989382