Year	Percent
1990	57.23
1991	57.63
1992	58
1993	58.31
1994	59.42
1995	60.22
1996	61.07
1997	61.25
1998	61.39
1999	61.29
2000	61.23
2001	61.24
2002	61.34
2003	62.49
2004	63.61
2005	64.69
2006	64.62
2007	64.38
2008	64.29
2009	63.51
2010	62.46
2011	61.57
2012	62.3
2013	62.36
2014	62.65
2015	61.9
2016	61.28
2017	60.9
2018	60.53
2019	60.14
2020	56.93