Year	Percent
1969-01-01	2.03876600198417
1970-01-01	1.41258924956405
1971-01-01	1.23853108826759
1972-01-01	1.16441848279074
1973-01-01	1.08489617598987
1974-01-01	1.34543615207231
1975-01-01	1.75242410549895
1976-01-01	1.80901774661527
1977-01-01	1.63816254582151
1978-01-01	2.06265552371872
1979-01-01	2.10419540254475
1980-01-01	1.85427695318009
1981-01-01	2.51560925624183
1982-01-01	3.46495914690694
1983-01-01	4.10756086309384
1984-01-01	3.80004518678982
1985-01-01	3.59938423546055
1986-01-01	3.13463150943443
1987-01-01	3.79492352401234
1988-01-01	3.56373374586505
1989-01-01	3.13262777407493
1990-01-01	3.24046173228391
1991-01-01	3.47567583625191
1992-01-01	3.59314564383555
1993-01-01	4.21746608135019
1994-01-01	3.57794177705799
1995-01-01	3.69978496409736
1996-01-01	4.13983054615580
1997-01-01	4.24240647147961
1998-01-01	4.23576622704515
1999-01-01	3.72500000000000
2000-01-01	3.52500000000000
2001-01-01	3.60000000000000
2002-01-01	3.97500000000000
2003-01-01	4.30000000000000
2004-01-01	5.47500000000000
2005-01-01	5.65000000000000
2006-01-01	5.25000000000000
2007-01-01	4.87500000000000
2008-01-01	4.12500000000000
2009-01-01	5.32500000000000
2010-01-01	4.82500000000000
2011-01-01	4.57500000000000
2012-01-01	4.87500000000000
2013-01-01	5.35000000000000
2014-01-01	5.65000000000000
2015-01-01	5.72500000000000
2016-01-01	6.02500000000000
2017-01-01	5.55000000000000