Year	constant 2011 PPP $ per kg of oil equivalent
1990	13.0190659857229
1991	13.1408632180585
1992	12.4731688108638
1993	12.9666632827871
1994	12.6644264537786
1995	12.7002407700873
1996	12.36632397725
1997	12.6655540029367
1998	11.7233270441861
1999	12.3595607918416
2000	12.5328249373625
2001	11.1183399679779
2002	12.5092905631012
2003	13.0205386287004
2004	14.1931529009816
2005	13.6421019209155
2006	13.8726709875738
2007	15.8713301562238
2008	17.391446317134
2009	15.9540394822849
2010	15.7780175550213
2011	16.1858274021949
2012	17.2097549375508
2013	18.7268755798175
2014	18.5501149153166