Year	PPP $ per kg of oil equivalent
1990	2.433325063875175
1991	2.4586511365781862
1992	2.5983708466010835
1993	2.685790359243604
1994	2.966285337717849
1995	3.061823869976121
1996	3.113991738621672
1997	3.2942271918479156
1998	3.6103307190116616
1999	3.9235832759479963
2000	4.214649488535538
2001	4.396351291216482
2002	4.70129602078393
2003	4.80011684120129
2004	5.2273547345084035
2005	5.467871027950052
2006	5.916878725112432
2007	6.587756935576951
2008	7.269934659693369
2009	7.795548972600123
2010	7.9023317395594
2011	8.458367906934498
2012	9.005638328026444
2013	9.500797844796487
2014	10.091159448346858