Year	PPP $ per kg of oil equivalent
1990	8.243859973787455
1991	8.947715377101108
1992	9.142230072109646
1993	9.281724159322536
1994	9.429560361986125
1995	9.301862713078672
1996	9.842272492304494
1997	10.0143984749334
1998	10.21725221372231
1999	10.703744596931152
2000	11.13891368140251
2001	10.940855755201529
2002	11.267600238049654
2003	11.421048052927928
2004	12.118379744491715
2005	12.823103090573976
2006	13.160426542973093
2007	13.851218013853167
2008	14.259956044818273
2009	14.326120181252842
2010	14.134825812201772
2011	14.80504390351782
2012	16.032505265365618
2013	17.03229199603758
2014	17.714853822731186