Year	Percent
1965-01-01	6.51
1966-01-01	6.91
1967-01-01	7.22
1968-01-01	7.75
1969-01-01	7.52
1970-01-01	7.82
1971-01-01	7.71
1972-01-01	7.38
1973-01-01	8.25
1974-01-01	9.74
1975-01-01	9.61
1976-01-01	8.75
1977-01-01	8.73
1978-01-01	8.21
1979-01-01	7.96
1980-01-01	9.20
1981-01-01	10.61
1982-01-01	9.92
1983-01-01	8.17
1984-01-01	8.02
1985-01-01	7.77
1986-01-01	7.33
1987-01-01	6.94
1988-01-01	6.67
1989-01-01	7.14
1990-01-01	8.74
1991-01-01	8.62
1992-01-01	8.27
1993-01-01	6.64
1994-01-01	6.69
1995-01-01	6.47
1996-01-01	5.30
1997-01-01	4.79
1998-01-01	4.29
1999-01-01	4.09
2000-01-01	5.31
2001-01-01	4.62
2002-01-01	4.40
2003-01-01	3.41
2004-01-01	3.41
2005-01-01	2.97
2006-01-01	3.64
2007-01-01	4.24
2008-01-01	4.10
2009-01-01	3.28
2010-01-01	2.47
2011-01-01	2.63
2012-01-01	1.48
2013-01-01	1.05
2014-01-01	0.95