Year	Percent
1990	58.12
1991	58.27
1992	59.51
1993	60.71
1994	61.87
1995	63.75
1996	65.52
1997	67.27
1998	68.03
1999	69.11
2000	67.4
2001	70.57
2002	72.47
2003	73.16
2004	74.93
2005	72.66
2006	75.59
2007	77.9
2008	77.95
2009	78.38
2010	79.08
2011	78.58
2012	78.4
2013	77.8
2014	76.97
2015	75.82
2016	75.44
2017	77.08
2018	77.56
2019	77.86
2020	65.17