Year	Percent
1990	75.93
1991	75.03
1992	74.09
1993	73.13
1994	72.15
1995	71.14
1996	70.13
1997	69.09
1998	68.03
1999	67.61
2000	67.18
2001	66.76
2002	66.32
2003	65.89
2004	65.44
2005	64.99
2006	64.55
2007	64.1
2008	63.65
2009	63.2
2010	62.75
2011	62.3
2012	61.85
2013	61.4
2014	60.95
2015	61.23
2016	61.4
2017	61.52
2018	61.57
2019	61.59