Year	constant 2021 PPP $ per kg of oil equivalent
1990	14.497568379447635
1991	14.65251858984546
1992	14.918111480607626
1993	14.80380818145478
1994	15.999308520528638
1995	15.743243890285251
1996	15.57267173100465
1997	15.773592509842885
1998	15.541677807183339
1999	16.122463055580276
2000	17.973158497419966
2001	16.570012216422178
2002	16.447101850008103
2003	16.349117099290737
2004	15.743965488283362
2005	14.116537721241068
2006	14.274348326997703
2007	14.270763642677
2008	14.721086483547216
2009	15.059852599211256
2010	16.142737883905827
2011	15.653285350722037
2012	15.566117082111809
2013	16.593268067670348
2014	17.121984011460263