Year	constant 2011 PPP $ per kg of oil equivalent
1990	10.3689845877417
1991	10.7152134494505
1992	10.2056344663621
1993	10.3736539874663
1994	10.4426829940631
1995	10.3897910062597
1996	10.3489459993005
1997	10.0648843525093
1998	10.0941374034138
1999	10.1823996111288
2000	9.87934621760946
2001	9.55900297112719
2002	9.47508600944794
2003	10.4042170454708
2004	10.2932620967854
2005	10.6562888310737
2006	10.890859224914
2007	10.6523323673784
2008	10.6185702802446
2009	9.03903421755134
2010	9.18519731685188
2011	8.80070972572053
2012	9.32462671273433
2013	10.3967798633737
2014	10.3954056203815