Year	Percent
1990	48.27
1991	49.13
1992	49.39
1993	49.5
1994	50.12
1995	50.4
1996	50.32
1997	50.41
1998	50.69
1999	51.85
2000	52.2
2001	50.72
2002	50.94
2003	51.05
2004	51.76
2005	53.17
2006	53
2007	53.57
2008	53.6
2009	53.38
2010	53.97
2011	53.07
2012	53.14
2013	53.49
2014	53.55
2015	53.45
2016	53.23
2017	53.38
2018	53.7
2019	53.91
2020	53.34