Year	constant 2021 PPP $ per kg of oil equivalent
1990	12.560708644770065
1991	12.589905299413513
1992	12.658408660712892
1993	13.022642465233373
1994	13.14477297590065
1995	13.021975889568326
1996	12.983076157933425
1997	13.107114607344313
1998	13.07425321596238
1999	12.878491688237666
2000	13.2180180044682
2001	13.112196455835724
2002	13.021660148326855
2003	12.886217829315232
2004	13.041493165266278
2005	13.005996493095429
2006	13.160158891614207
2007	13.494766707889273
2008	13.657813530224452
2009	13.473161014900638
2010	13.70439707111739
2011	13.9112583370663
2012	13.760760311294565
2013	13.790900367334386
2014	13.751154909727376