Year	Percent
1990	62.57
1991	62.96
1992	63.13
1993	63.19
1994	64.01
1995	64.5
1996	64.94
1997	65.49
1998	63.79
1999	63.72
2000	64.31
2001	64.59
2002	65.29
2003	65.17
2004	66.05
2005	66.09
2006	66.06
2007	66.01
2008	65.61
2009	64.95
2010	65.34
2011	65.72
2012	66.04
2013	66.27
2014	67.55
2015	67.96
2016	68.33
2017	68.84
2018	68.87
2019	69.11