Year	Percent
1985-01-01	18.70
1986-01-01	21.32
1987-01-01	20.47
1988-01-01	18.91
1989-01-01	18.04
1990-01-01	17.82
1991-01-01	19.73
1992-01-01	21.47
1993-01-01	22.36
1994-01-01	22.66
1995-01-01	23.14
1996-01-01	24.28
1997-01-01	27.27
1998-01-01	30.01
1999-01-01	32.94
2000-01-01	36.00
2001-01-01	38.25
2002-01-01	41.00
2003-01-01	43.59
2004-01-01	44.12
2005-01-01	43.07
2006-01-01	42.23
2007-01-01	41.71
2008-01-01	41.72
2009-01-01	46.32
2010-01-01	50.76
2011-01-01	48.91
2012-01-01	46.19
2013-01-01	44.75
2014-01-01	43.91
2015-01-01	44.95