Year	constant 2021 PPP $ per kg of oil equivalent
1990	14.6076653236411
1991	14.407461683822756
1992	13.491082984237657
1993	9.902311430529318
1994	9.899600845494222
1995	11.393640571501969
1996	12.572073828746912
1997	13.199154730606868
1998	13.853299396661004
1999	13.47680610577417
2000	13.520785166624451
2001	13.495651771044715
2002	14.662762539243872
2003	13.994361904799423
2004	15.091281804112263
2005	17.96327528726363
2006	18.26330454991458
2007	19.520677255928867
2008	20.04851188188147
2009	18.606783806413453
2010	18.51842451928799
2011	18.44856120551608
2012	18.24730502570614
2013	19.12725159284163
2014	18.97490833337667