Year	PPP $ per kg of oil equivalent
1990	1.2720139096493008
1991	1.1016013654183292
1992	1.2898457847855862
1993	2.2686797922797113
1994	3.8842915136959975
1995	3.553527250203887
1996	3.537381434215718
1997	3.5565639711751706
1998	3.7889737668563037
1999	4.105411453330234
2000	4.046351298677439
2001	4.554678686861306
2002	5.597016261841743
2003	6.162266863780636
2004	6.61341666274432
2005	6.477657044016405
2006	7.42210570430099
2007	7.773552989117445
2008	8.043659877233921
2009	8.001873256220437
2010	8.69986101294833
2011	8.50117553615673
2012	9.103712171121439
2013	9.851409156556974
2014	9.917422579867148