Year	Percent
1990	68.39
1991	68.39
1992	68.26
1993	68.2
1994	67.3
1995	67.07
1996	67.57
1997	67.41
1998	67.93
1999	67.91
2000	67.41
2001	67.79
2002	67.74
2003	67.83
2004	67.29
2005	67.03
2006	67.42
2007	67.72
2008	68.24
2009	68.28
2010	66.95
2011	67.46
2012	67.53
2013	67.56
2014	67.97
2015	68.21
2016	68.57
2017	68.38
2018	68.38
2019	68.07
2020	67.52