Year	Percent
1961-01-01	8.3130200000000000
1962-01-01	7.8468800000000005
1963-01-01	7.8365800000000005
1964-01-01	7.3631800000000010
1965-01-01	7.3631800000000010
1966-01-01	7.3631800000000010
1967-01-01	7.3631800000000010
1968-01-01	9.4716800000000010
1969-01-01	9.1410300000000000
1970-01-01	5.2804000000000000
1971-01-01	4.0879000000000000
1972-01-01	3.6164500000000000
1973-01-01	3.0035000000000000
1974-01-01	2.5202000000000000
1975-01-01	2.2942900000000000
1976-01-01	1.6944800000000000
1977-01-01	1.4365299999999999
1978-01-01	1.7353200000000000
1979-01-01	1.9013700000000000
1980-01-01	1.8628500000000000
1981-01-01	1.6444400000000001
1982-01-01	1.6808500000000000
1983-01-01	1.7781099999999999
1984-01-01	1.4496900000000000
1985-01-01	1.2108500000000000
1986-01-01	1.3404000000000000
1987-01-01	1.5685300000000000
1988-01-01	1.6728000000000000
1989-01-01	8.8222800000000010
1990-01-01	15.3843000000000000
1991-01-01	15.5345000000000000
1992-01-01	13.5956000000000000
1993-01-01	12.6295000000000000
1994-01-01	11.7847000000000000
1995-01-01	9.0385300000000000
1996-01-01	5.4116200000000000
1997-01-01	3.6911500000000000
1998-01-01	3.3025900000000004
1999-01-01	3.1753299999999998
2000-01-01	3.2388600000000000
2001-01-01	3.5363000000000000
2002-01-01	4.2269000000000000
2003-01-01	5.1597700000000000
2004-01-01	6.1244500000000000
2005-01-01	7.0689199999999990
2006-01-01	7.9411700000000000
2007-01-01	9.7060400000000000
2008-01-01	10.5769000000000000
2009-01-01	10.9478000000000000
2010-01-01	10.7542000000000000
2011-01-01	11.1617000000000000
2012-01-01	11.9255000000000000
2013-01-01	12.0324000000000000
2014-01-01	12.7039000000000000
2015-01-01	13.6443000000000000
2016-01-01	13.7149000000000000