Year	Percent
1990	63.24
1991	62.891
1992	62.439
1993	61.923
1994	61.394
1995	60.89
1996	60.922
1997	60.957
1998	60.971
1999	60.92
2000	60.783
2001	60.735
2002	60.529
2003	60.2
2004	59.805
2005	59.379
2006	59.22
2007	58.51
2008	57.795
2009	57.078
2010	56.358
2011	55.635
2012	54.909
2013	54.182
2014	53.453
2015	52.722
2016	51.99
2017	51.81
2018	51.631
2019	51.451
2020	51.271
2021	51.092
2022	50.912
2023	50.732
2024	50.553
2025	50.373
2026	50.193
2027	50.014
2028	49.834
2029	49.655
2030	49.475