Year	Percent
1980-01-01	5.110
1981-01-01	4.995
1982-01-01	5.825
1983-01-01	1.680
1984-01-01	5.585
1985-01-01	7.035
1986-01-01	4.240
1987-01-01	12.910
1988-01-01	8.945
1989-01-01	10.220
1990-01-01	8.365
1991-01-01	9.760
1992-01-01	8.135
1993-01-01	12.030
1994-01-01	17.500
1995-01-01	13.960
1996-01-01	16.130
1997-01-01	13.220
1998-01-01	15.340
1999-01-01	28.360
2000-01-01	10.110
2001-01-01	11.000
2002-01-01	13.005
2003-01-01	15.285
2004-01-01	10.990
2005-01-01	12.990
2006-01-01	10.165
2007-01-01	11.420
2008-01-01	8.110
2009-01-01	7.690
2010-01-01	11.555
2011-01-01	9.745
2012-01-01	10.540
2013-01-01	12.575
2014-01-01	14.080
2015-01-01	15.290