Year	Percent
1990	50.7
1991	51.88
1992	52.7
1993	52.13
1994	52.08
1995	50.29
1996	50.81
1997	51
1998	51.2
1999	52.06
2000	53.37
2001	52.82
2002	53.86
2003	53.15
2004	54.1
2005	54.8
2006	55.28
2007	55.01
2008	55.01
2009	57.28
2010	56.98
2011	56.85
2012	58.01
2013	58.28
2014	59.02
2015	59.36
2016	58.17
2017	58.67
2018	59.2
2019	59.92
2020	59.97