Year	PPP $ per kg of oil equivalent
1990	2.5436079165090524
1991	2.971367872076815
1992	2.9471640476681404
1993	3.231130446835142
1994	3.096920533378502
1995	3.245139720684762
1996	3.4415237403705072
1997	3.201689732351062
1998	3.2292024763725657
1999	3.447410290976227
2000	3.51488033083665
2001	3.5845502253088815
2002	3.6283408816990663
2003	3.707161787589477
2004	4.057199015105622
2005	3.8908807696309227
2006	3.9860170843661322
2007	4.237074905971311
2008	4.232579724136493
2009	4.496247678388307
2010	4.593020343584819
2011	4.779476622445752
2012	5.252806123079699
2013	4.954547346940953
2014	4.840925891191945