Year	Percent
1980-01-01	5.2750000000000000
1981-01-01	4.8550000000000000
1982-01-01	5.7250000000000000
1983-01-01	7.0450000000000000
1984-01-01	6.9500000000000000
1985-01-01	7.1350000000000000
1986-01-01	7.3950000000000000
1987-01-01	6.4800000000000000
1988-01-01	7.2100000000000000
1989-01-01	6.1700000000000000
1990-01-01	6.2900000000000000
1991-01-01	6.4650000000000000
1992-01-01	6.4200000000000000
1993-01-01	6.7829999999999995
1994-01-01	6.6200000000000000
1995-01-01	5.9400000000000000
1996-01-01	5.7300000000000000
1997-01-01	5.2250000000000000
1998-01-01	5.4900000000000000
1999-01-01	5.8900000000000000
2000-01-01	5.5100000000000000
2001-01-01	5.4850000000000000
2002-01-01	5.7100000000000000
2003-01-01	5.7500000000000000
2004-01-01	5.5700000000000000
2005-01-01	5.8400000000000000
2006-01-01	5.5400000000000000
2007-01-01	5.2900000000000000
2008-01-01	5.8500000000000000
2009-01-01	6.7000000000000000
2010-01-01	7.5600000000000000
2011-01-01	7.7211800000000000
2012-01-01	7.6836000000000000
2013-01-01	7.9200000000000000
2014-01-01	8.4600000000000000
2015-01-01	8.6300000000000000