Year	PPP $ per kg of oil equivalent
1990	5.399017852013697
1991	5.103592433210558
1992	5.562013427445084
1993	5.545328437936764
1994	5.7637306551397565
1995	6.119342468949712
1996	5.691039402416908
1997	6.476815668879143
1998	6.843351714211218
1999	7.398351551033948
2000	8.213446420232954
2001	8.216065331495793
2002	8.667467069985712
2003	8.268096540977517
2004	9.157088311219342
2005	9.79179004439013
2006	10.014068564361287
2007	10.76991482717452
2008	11.788708722659152
2009	12.114048012385778
2010	12.246683418776207
2011	13.74637773894501
2012	14.492248410306532
2013	14.950977376048982
2014	16.67544679831915
2015	17.412868552519118