Year	Percent
1989-01-01	26.830
1990-01-01	24.600
1991-01-01	26.460
1992-01-01	24.875
1993-01-01	26.640
1994-01-01	27.450
1995-01-01	28.535
1996-01-01	29.840
1997-01-01	25.610
1998-01-01	27.650
1999-01-01	27.070
2000-01-01	25.810
2001-01-01	27.005
2002-01-01	28.940
2003-01-01	31.905
2004-01-01	32.765
2005-01-01	31.055
2006-01-01	28.800
2007-01-01	28.640
2008-01-01	23.480
2009-01-01	29.070
2010-01-01	30.890
2011-01-01	29.500
2012-01-01	32.100
2013-01-01	31.100
2014-01-01	29.070
2015-01-01	28.670