Year	Percent
1990	60.6
1991	60.79
1992	61.35
1993	61.96
1994	61.95
1995	61.93
1996	62.04
1997	63.57
1998	63.26
1999	62.54
2000	62.5
2001	61.92
2002	61.38
2003	61.8
2004	62.43
2005	63.4
2006	64.23
2007	64.4
2008	64.08
2009	64.06
2010	63.88
2011	64.02
2012	64.78
2013	64.63
2014	64.03
2015	64.14
2016	64.16
2017	64.04
2018	64.35
2019	65.25