Year Hours 1977-01-01 171.0000 1978-01-01 169.0000 1979-01-01 168.0000 1980-01-01 166.0000 1981-01-01 158.5000 1982-01-01 155.2500 1983-01-01 154.5000 1984-01-01 151.0000 1985-01-01 150.2500 1986-01-01 151.2500 1987-01-01 149.2500 1988-01-01 150.2500 1989-01-01 147.2500 1990-01-01 146.9250 1991-01-01 146.1250 1992-01-01 145.9000 1993-01-01 145.1250 1994-01-01 145.6750 1995-01-01 145.3750 1996-01-01 144.2225 1997-01-01 143.3750 1998-01-01 142.6350 1999-01-01 142.2550 2000-01-01 140.4250 2001-01-01 140.0000 2002-01-01 139.5500 2003-01-01 138.9000 2004-01-01 137.7500 2005-01-01 136.9000 2006-01-01 136.0250 2007-01-01 135.4750 2008-01-01 135.2250 2009-01-01 132.5250 2010-01-01 132.1500 2011-01-01 130.9500 2012-01-01 130.2000 2013-01-01 129.7250 2014-01-01 129.1500 2015-01-01 129.1250 2016-01-01 128.7500 2017-01-01 128.9250