Year	Percent
1979-01-01	43.5817515250000
1980-01-01	44.7639801083333
1981-01-01	44.7446896583333
1982-01-01	44.6414085000000
1983-01-01	44.6594959166667
1984-01-01	45.2975918500000
1985-01-01	46.2751346500000
1986-01-01	48.2918914416667
1987-01-01	48.9351748083333
1988-01-01	49.8609401333333
1989-01-01	51.2242193750000
1990-01-01	52.2438483083333
1991-01-01	51.9788287666667
1992-01-01	51.9399662916667
1993-01-01	51.7006997333333
1994-01-01	52.5950062833333
1995-01-01	53.5992785333333
1996-01-01	53.7903634333333
1997-01-01	53.5819023666667
1998-01-01	53.6370218416667
1999-01-01	53.6272860916667
2000-01-01	54.5076150500000
2001-01-01	55.0487116666667
2002-01-01	55.2403999000000
2003-01-01	55.9147921750000
2004-01-01	55.6861787583333
2005-01-01	56.9689255083333
2006-01-01	57.5183915583333
2007-01-01	58.0686593666667
2008-01-01	58.5476174333333
2009-01-01	58.7467272666667
2010-01-01	58.6123732250000
2011-01-01	58.8639881333333
2012-01-01	58.7715698166667
2013-01-01	58.6905251166667
2014-01-01	58.6683498083333
2015-01-01	59.1253767416667
2016-01-01	59.3526147333333
2017-01-01	59.8509626916667