Year	Percent
1975-01-01	5.82496999999999950
1976-01-01	4.54560000000000000
1977-01-01	5.58285000000000000
1978-01-01	7.22452000000000000
1979-01-01	9.33794000000000000
1980-01-01	9.02283000000000000
1981-01-01	8.99439000000000000
1982-01-01	8.63114000000000000
1983-01-01	8.02903000000000000
1984-01-01	8.72219000000000000
1985-01-01	7.97906000000000050
1986-01-01	6.85015000000000000
1987-01-01	6.99715000000000000
1988-01-01	6.25370000000000000
1989-01-01	6.11518000000000050
1990-01-01	5.68963000000000000
1991-01-01	5.28638000000000000
1992-01-01	4.42575000000000000
1993-01-01	4.54132000000000000
1994-01-01	3.81745000000000000
1995-01-01	3.34580000000000000
1996-01-01	3.02388000000000000
1997-01-01	2.97960999999999960
1998-01-01	2.84848000000000000
1999-01-01	0.19467300000000000
2000-01-01	0.21860500000000002
2001-01-01	0.28139400000000003
2002-01-01	0.22998800000000000
2003-01-01	0.23261199999999999
2004-01-01	0.20344000000000000
2005-01-01	0.19602100000000000
2006-01-01	0.21094400000000000
2007-01-01	0.25401500000000000
2008-01-01	0.24462500000000000
2009-01-01	0.24522100000000000
2010-01-01	0.21695599999999998
2011-01-01	0.22017100000000000
2012-01-01	0.21322600000000003
2013-01-01	0.19749600000000000
2014-01-01	0.19044500000000000
2015-01-01	0.18508000000000000
2016-01-01	0.20693000000000003
2017-01-01	0.20803100000000000