Year	Percent
1990	65.949
1991	66.09
1992	65.787
1993	65.608
1994	65.352
1995	65.106
1996	64.901
1997	64.715
1998	64.499
1999	64.028
2000	63.401
2001	62.851
2002	62.253
2003	61.558
2004	60.862
2005	60.158
2006	59.472
2007	58.835
2008	58.276
2009	57.716
2010	57.205
2011	56.89
2012	56.515
2013	56.115
2014	55.752
2015	55.437
2016	55.203
2017	55.122
2018	55.054
2019	54.997
2020	54.952
2021	54.932
2022	54.924
2023	54.923
2024	54.92
2025	54.909
2026	54.901
2027	54.885
2028	54.862
2029	54.836
2030	54.807