Year	constant 2011 PPP $ per kg of oil equivalent
1990	11.9972511584829
1991	12.385501597169
1992	11.7663725144233
1993	11.6886469683757
1994	11.5041085459898
1995	10.8493136019767
1996	11.3395916886222
1997	11.2418886808325
1998	10.9018813500707
1999	10.5532081899092
2000	10.878002221388
2001	11.0062594970577
2002	10.6462456647533
2003	10.8430602892075
2004	10.7349142222939
2005	10.5570598289411
2006	11.2778139900115
2007	11.4780775435479
2008	11.8045234072814
2009	11.6071564084735
2010	12.2550601957711
2011	12.3754326533267
2012	12.6560565369913
2013	12.4666389895748
2014	12.7911213088147
2015	12.4820842024383