Year	Percent
1990	57.094
1991	57.984
1992	60.811
1993	63.338
1994	64.902
1995	65.406
1996	64.852
1997	60.039
1998	58.578
1999	57.512
2000	55.777
2001	55.925
2002	55.857
2003	58.658
2004	58.573
2005	58.409
2006	58.145
2007	57.802
2008	57.629
2009	57.526
2010	57.25
2011	56.798
2012	56.294
2013	55.67
2014	55.574
2015	55.502
2016	55.543
2017	55.449
2018	55.355
2019	55.261
2020	55.167
2021	55.072
2022	54.978
2023	54.884
2024	54.79
2025	54.696
2026	54.602
2027	54.508
2028	54.414
2029	54.319
2030	54.225