Year	Percent
1990	42.22
1991	42.41
1992	42.32
1993	42.32
1994	42.46
1995	42.4
1996	42.42
1997	42.31
1998	42.25
1999	42.18
2000	41.95
2001	41.88
2002	41.83
2003	41.8
2004	41.79
2005	42.03
2006	42.29
2007	42.58
2008	42.9
2009	43.24
2010	43.6
2011	43.97
2012	44.34
2013	44.72
2014	45.09
2015	45.25
2016	45.34
2017	45.41
2018	45.47
2019	45.54
2020	44.29