Year	PPP $ per kg of oil equivalent
1990	2.6513120754883635
1991	2.6904082319614404
1992	2.713372308701498
1993	2.759142761737656
1994	2.844305068767839
1995	2.943100352502427
1996	2.9863177270037675
1997	3.135314884744187
1998	3.3113184006732155
1999	3.4340180455699434
2000	3.552546911612051
2001	3.7524195351624137
2002	3.8733450324642744
2003	3.878265538675841
2004	4.01224269430391
2005	4.313355577041597
2006	4.626172487004416
2007	4.818389477734813
2008	4.9270157805362444
2009	4.984585051017387
2010	5.1485055250728635
2011	5.266563879624481
2012	5.468603935542257
2013	5.720576917288002
2014	5.793186503338841
2015	5.853502968940111