Year	constant 2021 PPP $ per kg of oil equivalent
1990	12.096976452477083
1991	12.806735554768615
1992	13.144376609912921
1993	14.181801368950989
1994	14.109526738585092
1995	13.513367045941669
1996	13.75269649740832
1997	14.406894009675483
1998	14.466804184920525
1999	13.7416683448077
2000	13.473511648632229
2001	13.539459251192785
2002	12.413116688435938
2003	12.626345598414048
2004	12.601790802926486
2005	13.635334788201687
2006	13.541989092516104
2007	14.573009826938486
2008	14.400405199541389
2009	13.933297684981625
2010	14.729160740886446
2011	15.249484569959115
2012	15.039816078575994
2013	14.996201073900876
2014	14.011492374341376