Year	Percent
1990	65.28
1991	65.87
1992	67.2
1993	68.4
1994	70.27
1995	71.15
1996	72.07
1997	71.83
1998	72.94
1999	73.51
2000	73.16
2001	72.14
2002	70.91
2003	69.88
2004	68.81
2005	66.93
2006	65.02
2007	63.05
2008	61.02
2009	58.96
2010	57.47
2011	57.83
2012	55.58
2013	56.33
2014	55.42
2015	58.07
2016	56.24
2017	54.93
2018	51.91
2019	55.54