Year	Percent
1990	72.99
1991	72.48
1992	71.67
1993	70.55
1994	70.29
1995	70.77
1996	70.4
1997	70.94
1998	71.47
1999	71.56
2000	71.99
2001	69.98
2002	67.89
2003	65.7
2004	63.43
2005	61.08
2006	58.62
2007	56.11
2008	53.54
2009	50.92
2010	48.27
2011	48.34
2012	48.23
2013	48.15
2014	47.6
2015	47.24
2016	47.12
2017	47.04
2018	47.19
2019	47.01
2020	46.71