Year	% of total energy use
1971	0.5509267054322236
1972	0.6231936987429688
1973	0.6175661017319062
1974	0.7976277010562862
1975	0.923565192642455
1976	0.7908901718275071
1977	0.9679455748129183
1978	1.3455971785592789
1979	1.5826403677407446
1980	1.2361417136943376
1981	1.6099796590434332
1982	1.6614005229352538
1983	1.9022458679479832
1984	1.7809363272981011
1985	1.9955043144079472
1986	4.867590473954269
1987	4.795883601939562
1988	4.721217241552527
1989	4.672803350153141
1990	2.0187262635879026
1991	2.1311914197981676
1992	2.148956749840851
1993	2.228188975733191
1994	2.3077663511823445
1995	2.1263621809895126
1996	2.1689793479723383
1997	1.9924253576121962
1998	1.9508405176762686
1999	1.4543561516473447
2000	0.8902993752512164
2001	1.4368384351400811
2002	1.756804042786055
2003	1.9895248071527976
2004	1.8066171810302598
2005	1.7389231833782024
2006	1.7945636411017676
2007	1.8770537065359094
2008	1.6313285050513497
2009	1.3567219053038788
2010	1.7972407905832968
2011	1.7698265520853143
2012	2.0493762728385825
2013	1.9817307119414194
2014	2.2389407749930816