Year	Percent
1990	64.53
1991	64.58
1992	64.53
1993	62.03
1994	60.05
1995	59.08
1996	57.9
1997	57.1
1998	58.01
1999	59.17
2000	59.47
2001	59.39
2002	59.42
2003	60.43
2004	60.13
2005	61.18
2006	61.75
2007	61.52
2008	61.14
2009	61.16
2010	61.82
2011	62.29
2012	63.49
2013	64.33
2014	66.6
2015	68.37
2016	69.95
2017	71.09
2018	71.93
2019	72.57