Year	Percent
1990	70.39
1991	70.35
1992	70.35
1993	70.47
1994	70.12
1995	70.2
1996	70.11
1997	69.86
1998	69.65
1999	69.7
2000	69.48
2001	69.85
2002	70.35
2003	70.34
2004	70.35
2005	70.27
2006	69.99
2007	69.96
2008	69.94
2009	70.14
2010	70.4
2011	70.38
2012	70.33
2013	70.33
2014	70.4
2015	70.62
2016	70.64
2017	70.58
2018	70.59
2019	70.55