Year	Percent
1990	66.907
1991	66.755
1992	67.142
1993	66.816
1994	66.504
1995	66.363
1996	66.179
1997	66.097
1998	65.792
1999	65.672
2000	65.518
2001	65.874
2002	65.41
2003	65.309
2004	67.031
2005	66.212
2006	65.413
2007	64.621
2008	63.827
2009	63.023
2010	62.206
2011	61.386
2012	60.553
2013	59.704
2014	58.841
2015	59.274
2016	58.897
2017	58.756
2018	58.611
2019	58.463
2020	58.319
2021	58.187
2022	58.059
2023	57.942
2024	57.848
2025	57.786
2026	57.761
2027	57.765
2028	57.788
2029	57.822
2030	57.861