Year	PPP $ per kg of oil equivalent
1990	7.445505258105098
1991	7.393437734080736
1992	7.207528216922987
1993	7.055393510752381
1994	6.991621864336269
1995	7.145300271526825
1996	7.311030224008291
1997	7.528596721811217
1998	7.937151634959482
1999	8.128347308627943
2000	8.678355414339665
2001	8.386549806021455
2002	8.151879893077245
2003	8.521259771875776
2004	8.985006259642097
2005	9.244693883662626
2006	9.41965857024919
2007	9.66499075438751
2008	9.659885561961813
2009	9.217776919230813
2010	9.209636531719534
2011	9.698713157005745
2012	9.584504064342998
2013	9.736043452005077
2014	9.352649633397764