Year	Percent
1990	67.04
1991	67.37
1992	67.63
1993	67.92
1994	68.11
1995	67.83
1996	68.13
1997	68.63
1998	68.95
1999	68.89
2000	68.97
2001	68.85
2002	68.31
2003	68.92
2004	69.53
2005	68.91
2006	69.27
2007	68.62
2008	67.96
2009	68.32
2010	67.65
2011	67.96
2012	68.04
2013	67.78
2014	67.05
2015	67.47
2016	67.86
2017	68.23
2018	69.21
2019	69.37