Year	PPP $ per kg of oil equivalent
1990	3.7538808966545507
1991	3.448867268301466
1992	3.7557471061170835
1993	3.656285144695812
1994	3.773211102314623
1995	3.807187932363547
1996	3.8134947994499457
1997	4.28619781177819
1998	4.595914237330944
1999	4.583247699175026
2000	5.247689634514605
2001	5.0449568256202175
2002	4.854545375171943
2003	4.959618051806918
2004	5.149245272656185
2005	5.7083573125645595
2006	6.315486981506525
2007	6.773257902844217
2008	7.905572690060398
2009	8.358440694862184
2010	8.870220493002654
2011	9.066537202655411
2012	8.182218599984907
2013	8.037596272132761
2014	7.244277848196241