Year	Percent
1990	69.53
1991	69.931
1992	70.262
1993	70.629
1994	70.536
1995	70.509
1996	70.618
1997	70.447
1998	70.175
1999	69.757
2000	69.201
2001	68.533
2002	67.823
2003	66.997
2004	66.278
2005	65.699
2006	65.242
2007	64.834
2008	64.575
2009	64.22
2010	63.79
2011	63.466
2012	63.129
2013	62.93
2014	62.646
2015	62.276
2016	61.968
2017	61.6
2018	61.228
2019	60.846
2020	60.46
2021	60.07
2022	59.67
2023	59.25
2024	58.797
2025	58.31
2026	57.848
2027	57.372
2028	56.892
2029	56.429
2030	55.987