Year	constant 2021 PPP $ per kg of oil equivalent
1990	15.046302545508944
1991	14.929693110236581
1992	15.057517675075948
1993	16.469126336129126
1994	16.044496834140695
1995	14.009721622440482
1996	13.531614486801946
1997	13.598484671225586
1998	13.666667580054272
1999	14.469283039277498
2000	13.201666938240068
2001	12.963923193890537
2002	13.938852691434626
2003	14.130763758471936
2004	15.63154236346394
2005	15.78805485481566
2006	16.40046007690955
2007	14.772510125919618
2008	17.088198730699123
2009	14.50256786298587
2010	14.925341669624485
2011	15.290069454001353
2012	16.383394595979322
2013	16.302609702430125
2014	15.884580688304212