Year	Percent
1991	45.47
1992	44.22
1993	43.35
1994	42.45
1995	41.81
1996	41.78
1997	41.67
1998	41.78
1999	42.16
2000	42.54
2001	43.3
2002	43.89
2003	44.43
2004	45.63
2005	45.17
2006	45.58
2007	45.66
2008	45.64
2009	44.55
2010	44.01
2011	43.96
2012	43.69
2013	42.66
2014	42.62
2015	42.95
2016	43.52
2017	44.05
2018	44.44
2019	44.77
2020	43.89