Year	Percent
1975-01-01	1.490
1976-01-01	1.230
1977-01-01	0.910
1978-01-01	1.090
1979-01-01	0.870
1980-01-01	0.975
1981-01-01	0.920
1982-01-01	0.740
1983-01-01	0.670
1984-01-01	0.910
1985-01-01	1.770
1986-01-01	3.620
1987-01-01	4.860
1988-01-01	5.795
1989-01-01	6.230
1990-01-01	4.640
1991-01-01	5.660
1992-01-01	3.180
1993-01-01	3.940
1994-01-01	4.880
1995-01-01	4.810
1996-01-01	5.450
1997-01-01	9.545
1998-01-01	16.720
1999-01-01	32.610
2000-01-01	27.360
2001-01-01	16.820
2002-01-01	15.120
2003-01-01	4.560
2004-01-01	6.560
2005-01-01	11.770
2006-01-01	18.930
2007-01-01	28.290
2008-01-01	27.820
2009-01-01	18.190
2010-01-01	12.560
2011-01-01	10.580
2012-01-01	7.330
2013-01-01	8.210
2014-01-01	15.345
2015-01-01	6.150