Year % of total energy use 1971 4.424253111141422 1972 4.3120716391502025 1973 2.908880410770962 1974 3.0092114605570632 1975 2.205991695214839 1976 2.005337879152154 1977 2.4945456384551457 1978 2.4411894183050715 1979 2.556550036708174 1980 2.4097236761408314 1981 1.62161365879528 1982 0.870241002199485 1983 0.7034760040807935 1984 0.51904706152017 1985 0.6762876989616857 1986 0.86773171903243 1987 1.0854230212485898 1988 1.1731684072930104 1989 1.3354064150561027 1990 1.1686280964702507 1991 1.2469916971633608 1992 0.9578859580357041 1993 0.41949083325322534 1994 0.6897657957993166 1995 0.4956555705219492 1996 1.499915619837052 1997 1.503753361462662 1998 1.3964112961147235 1999 0.572060894369286 2000 0.6091492050129691 2001 0.7089342998280004 2002 0.6991348697722748 2003 1.1076877790842563 2004 1.0195120418970625 2005 0.6273821177426401 2006 0.6523671150293503 2007 0.6808495578495246 2008 0.6856623010069641 2009 1.6503721524161779 2010 2.0741416291047132 2011 1.285868840797599 2012 1.0873479909522423 2013 1.8714587741452917 2014 1.616762345081126