Year	Percent
1990	59.22
1991	58.978
1992	58.736
1993	58.493
1994	58.25
1995	58.007
1996	57.763
1997	57.519
1998	57.274
1999	57.029
2000	56.784
2001	56.538
2002	56.292
2003	56.046
2004	55.799
2005	55.552
2006	55.305
2007	55.058
2008	54.81
2009	55.39
2010	54.972
2011	54.436
2012	53.898
2013	53.36
2014	53.343
2015	53.327
2016	55.25
2017	54.978
2018	54.707
2019	54.435
2020	54.163
2021	53.892
2022	53.62
2023	53.348
2024	53.077
2025	52.805
2026	52.533
2027	52.262
2028	51.99
2029	51.718
2030	51.447