Year	Percent
1990	46.34
1991	45.71
1992	45.21
1993	44.69
1994	44.15
1995	43.6
1996	43.05
1997	43.26
1998	43.51
1999	43.82
2000	44.21
2001	44.74
2002	45.33
2003	45.99
2004	46.7
2005	47.47
2006	46.38
2007	45.36
2008	43.13
2009	43.61
2010	42.9
2011	42.48
2012	42.1
2013	41.73
2014	41.34
2015	42.44
2016	43.94
2017	44.87
2018	44.95
2019	45.16
2020	42.42