Year	Percent
1990	67.475
1991	67.361
1992	67.273
1993	67.178
1994	67.218
1995	67.305
1996	66.139
1997	64.77
1998	63.26
1999	61.683
2000	62.702
2001	62.156
2002	62.472
2003	62.768
2004	62.626
2005	61.766
2006	61.774
2007	61.673
2008	61.532
2009	61.422
2010	61.346
2011	61.168
2012	60.201
2013	61.4
2014	59.771
2015	60.281
2016	60.418
2017	60.443
2018	60.472
2019	60.465
2020	60.397
2021	60.287
2022	60.11
2023	59.894
2024	59.684
2025	59.512
2026	59.385
2027	59.297
2028	59.22
2029	59.109
2030	58.933