Year	Percent
1990	68.09
1991	67.87
1992	67.91
1993	67.61
1994	67.08
1995	66.77
1996	66.32
1997	66.06
1998	66.11
1999	66.16
2000	67.16
2001	68.19
2002	69.19
2003	70.18
2004	71.16
2005	70.46
2006	69.8
2007	69.12
2008	68.43
2009	67.72
2010	66.98
2011	66.32
2012	66.17
2013	66.28
2014	66.37
2015	66.43
2016	66.51
2017	66.43
2018	66.29
2019	66.38