Year	Percent
1990	52.128
1991	52.263
1992	53.179
1993	54.301
1994	55.395
1995	56.149
1996	56.278
1997	56.228
1998	56.027
1999	55.941
2000	56.989
2001	57.888
2002	58.719
2003	59.5
2004	60.266
2005	61.051
2006	61.84
2007	62.678
2008	62.287
2009	61.864
2010	61.376
2011	60.765
2012	61.104
2013	61.323
2014	61.923
2015	62.517
2016	62.963
2017	62.908
2018	62.791
2019	62.625
2020	62.413
2021	62.152
2022	61.848
2023	61.498
2024	61.102
2025	60.664
2026	60.194
2027	59.687
2028	59.181
2029	58.728
2030	58.362