Year	Percent
1990	68.16
1991	68.59
1992	68.99
1993	68.17
1994	67.32
1995	66.43
1996	65.58
1997	64.7
1998	63.74
1999	62.65
2000	61.38
2001	63.78
2002	63.15
2003	61.81
2004	63.02
2005	62.4
2006	64.88
2007	66.72
2008	68.31
2009	67.57
2010	66.72
2011	65.99
2012	67.07
2013	68.37
2014	69.03
2015	69.4
2016	68.8
2017	71.48
2018	71.67
2019	73.37