Year	constant 2011 PPP $ per kg of oil equivalent
1990	9.58852123703509
1991	9.65349463820527
1992	9.63419760040427
1993	9.92678067889604
1994	9.86822474535558
1995	9.8790590425864
1996	9.81045246690545
1997	9.93932857453866
1998	9.84777602410859
1999	9.7229892895216
2000	9.9699803162211
2001	9.89885571065015
2002	9.73477155384599
2003	9.6769285426994
2004	9.84273935571439
2005	9.88288511747686
2006	9.95528233428739
2007	10.3212150845631
2008	10.3858815035525
2009	10.2578268701137
2010	10.3239857921245
2011	10.5781943703801
2012	10.4406408254216
2013	10.5383909325108
2014	10.7659915273754