Year	% of total energy use
1971	2.018371558998514
1972	2.327019825925983
1973	2.3170137812682756
1974	2.687324291329539
1975	2.7656100039723075
1976	2.913821089097019
1977	3.110142813799415
1978	2.9843453267276314
1979	2.9361869005172605
1980	2.940900925724892
1981	2.9301333169351658
1982	2.9211889827454023
1983	2.7999186533719067
1984	2.776643435690387
1985	2.893724928885354
1986	2.879827173828927
1987	2.7552424737864905
1988	2.8084436033852898
1989	2.780587842100248
1990	2.0843758672896597
1991	2.0454954352662584
1992	2.010685975844206
1993	2.0228447896760517
1994	1.9574029755083604
1995	1.9528102511307548
1996	1.8389074709292232
1997	1.6692626852521104
1998	1.592696676308435
1999	1.5937858116756365
2000	1.8265760573116663
2001	2.0083727532064626
2002	1.981647897302871
2003	2.1928737207543776
2004	2.3815397973128984
2005	2.3809780325696437
2006	2.3645816035021934
2007	2.400545809449568
2008	2.3371731222363787
2009	2.288088029068056
2010	2.5436154292840873
2011	2.7924165358397466
2012	3.059636437996477
2013	3.1937133501123185
2014	3.006613368045695