Year	constant 2011 PPP $ per kg of oil equivalent
1995	4.06326740314689
1996	3.46304132228466
1997	3.52139502988269
1998	3.61584548613879
1999	4.35245724934284
2000	4.34597930153278
2001	4.18555749876766
2002	4.22222971805554
2003	4.21142595775995
2004	4.22222779278076
2005	5.01767191836591
2006	5.18715495211006
2007	5.67326524239711
2008	5.90970709798728
2009	6.3840270110306
2010	6.24301721057472
2011	6.14398432441702
2012	6.79058052366587
2013	6.81670324549606
2014	7.54295543581264