Year	Percent
1990	73.63
1991	73.55
1992	73.388
1993	72.384
1994	72.147
1995	71.824
1996	70.886
1997	70.748
1998	70.224
1999	69.508
2000	69.099
2001	68.195
2002	67.802
2003	67.237
2004	67.442
2005	67.325
2006	67.221
2007	67.122
2008	66.925
2009	66.216
2010	66.369
2011	66.707
2012	67.015
2013	66.901
2014	66.901
2015	67.049
2016	66.578
2017	66.178
2018	65.789
2019	65.409
2020	65.03
2021	64.657
2022	64.298
2023	63.927
2024	63.508
2025	63.018
2026	62.473
2027	61.865
2028	61.204
2029	60.514
2030	59.814