Year	constant 2011 PPP $ per kg of oil equivalent
1990	9.83799700059157
1991	10.0604969660576
1992	9.88732629354
1993	9.85309335412172
1994	9.77786503619745
1995	9.89552415870751
1996	9.86311718258178
1997	9.91303916066041
1998	9.78082674153909
1999	10.0415497005924
2000	9.90931143861227
2001	9.98064018150718
2002	10.2561010510487
2003	10.5456202060415
2004	10.8684814840686
2005	10.7369166907408
2006	11.3527699339826
2007	11.7282720418387
2008	11.6123796429495
2009	11.4846454372462
2010	11.5732493486425
2011	10.8570994975138
2012	10.1381325453043
2013	11.1588183798522
2014	11.338412566072
2015	11.0604482508405