Year	PPP $ per kg of oil equivalent
1990	6.457009408719036
1991	6.746719766431756
1992	7.02554619075561
1993	7.1369684310702715
1994	7.878018143687199
1995	7.91446645983208
1996	7.97204153709905
1997	8.214145339002142
1998	8.184333726248902
1999	8.610322814558359
2000	9.81612995724554
2001	9.25356794625506
2002	9.327661616726079
2003	9.455151689743417
2004	9.35002173548517
2005	8.646387026265241
2006	9.012667375567101
2007	9.254519181370373
2008	9.730485631788621
2009	10.015803383833354
2010	10.86646721116533
2011	10.754382443496862
2012	12.31122586769657
2013	13.357127061358138
2014	13.368274840118293