Year	Percent
1990	69.085
1991	68.696
1992	67.149
1993	66.024
1994	68.993
1995	65.749
1996	64.86
1997	64.534
1998	64.962
1999	65.422
2000	65.426
2001	64.875
2002	63.706
2003	63.123
2004	62.214
2005	61.545
2006	60.892
2007	60.554
2008	60.104
2009	59.957
2010	59.618
2011	59.221
2012	58.642
2013	58.263
2014	57.691
2015	57.123
2016	56.572
2017	56.344
2018	56.115
2019	55.887
2020	55.659
2021	55.43
2022	55.202
2023	54.974
2024	54.745
2025	54.517
2026	54.289
2027	54.06
2028	53.832
2029	53.604
2030	53.375