Year	Percent
1980-01-01	47.466300000000000
1981-01-01	50.144700000000000
1982-01-01	34.349300000000000
1983-01-01	32.341400000000000
1984-01-01	30.420500000000000
1985-01-01	29.775000000000000
1986-01-01	30.082100000000000
1987-01-01	31.375100000000000
1988-01-01	26.040300000000000
1989-01-01	21.408600000000000
1990-01-01	22.183100000000000
1991-01-01	21.060300000000000
1992-01-01	21.053100000000000
1993-01-01	22.787600000000000
1994-01-01	22.373700000000000
1995-01-01	22.668800000000000
1996-01-01	23.887600000000000
1997-01-01	25.725900000000000
1998-01-01	29.076600000000000
1999-01-01	31.922100000000000
2000-01-01	33.883400000000000
2001-01-01	36.921400000000000
2002-01-01	37.281000000000000
2003-01-01	35.789900000000000
2004-01-01	34.560200000000000
2005-01-01	35.918400000000000
2006-01-01	37.745300000000000
2007-01-01	38.422600000000000
2008-01-01	41.415200000000000
2009-01-01	44.255700000000000
2010-01-01	45.553999999999995
2011-01-01	46.764800000000000
2012-01-01	48.839000000000000
2013-01-01	50.387800000000000
2014-01-01	51.943200000000000
2015-01-01	53.597000000000000
2016-01-01	55.833000000000000