Year	PPP $ per kg of oil equivalent
1990	6.2381793091802615
1991	6.585506475070208
1992	6.46389954184765
1993	6.453627600548499
1994	6.267579644007318
1995	5.968852453599331
1996	5.899960590043563
1997	5.775604212988775
1998	6.068645873737661
1999	6.28949526362511
2000	5.893740194860013
2001	7.875825050200306
2002	6.837530272459141
2003	6.888417597015172
2004	7.359878978307337
2005	7.267361976123424
2006	6.2726885024680685
2007	8.268537322323137
2008	8.411513780195842
2009	8.397752818979267
2010	8.124679426222764
2011	8.260707899431274
2012	7.9493529441038975
2013	9.021342153947527
2014	9.17656018439889