Year	Percent
1991	73.291
1992	74.063
1993	74.674
1994	75.177
1995	75.62
1996	74.895
1997	74.1
1998	73.232
1999	72.306
2000	71.373
2001	70.1
2002	68.847
2003	67.655
2004	66.576
2005	65.643
2006	65.87
2007	66.184
2008	66.572
2009	67.008
2010	67.434
2011	67.779
2012	68.057
2013	68.245
2014	68.316
2015	68.257
2016	67.755
2017	67.538
2018	67.348
2019	67.184
2020	67.065
2021	66.992
2022	66.951