Year	Percent
1990	70.51
1991	70.73
1992	70.97
1993	71.22
1994	71.31
1995	71.29
1996	71.38
1997	71.48
1998	71.49
1999	71.52
2000	71.59
2001	71.67
2002	71.69
2003	71.67
2004	71.63
2005	71.6
2006	70.58
2007	69.54
2008	68.48
2009	67.39
2010	66.3
2011	65.17
2012	64.02
2013	63.99
2014	63.93
2015	63.87
2016	63.86
2017	63.8
2018	63.7
2019	63.59
2020	61.38