Year	Percent
1990	63.43
1991	63.4
1992	62.96
1993	62.89
1994	63.67
1995	64.24
1996	65.04
1997	64.87
1998	64.45
1999	64.55
2000	64.7
2001	65.36
2002	66.07
2003	65.8
2004	66.37
2005	67.17
2006	67.73
2007	67.98
2008	67.86
2009	67.48
2010	67.21
2011	67.52
2012	67.33
2013	67.57
2014	68.4
2015	68.34
2016	69.33
2017	70.09
2018	70.01
2019	69.6
2020	69.53