Year	Percent
1980-01-01	2.065
1981-01-01	2.055
1982-01-01	2.240
1983-01-01	2.540
1984-01-01	2.710
1985-01-01	3.420
1986-01-01	3.590
1987-01-01	3.915
1988-01-01	3.070
1989-01-01	2.920
1990-01-01	3.900
1991-01-01	3.795
1992-01-01	5.900
1993-01-01	7.030
1994-01-01	6.750
1995-01-01	7.270
1996-01-01	7.275
1997-01-01	8.065
1998-01-01	8.890
1999-01-01	9.970
2000-01-01	9.950
2001-01-01	10.960
2002-01-01	12.700
2003-01-01	13.070
2004-01-01	12.810
2005-01-01	10.970
2006-01-01	11.385
2007-01-01	10.155
2008-01-01	8.625
2009-01-01	11.675
2010-01-01	12.050
2011-01-01	11.760
2012-01-01	13.430
2013-01-01	14.560
2014-01-01	14.540
2015-01-01	17.365