Year	Percent
1990	57.07
1991	57.928
1992	58.78
1993	59.628
1994	60.47
1995	60.382
1996	60.39
1997	60.402
1998	60.343
1999	60.253
2000	60.174
2001	60.088
2002	60.005
2003	59.961
2004	59.99
2005	59.962
2006	60.006
2007	60.15
2008	60.08
2009	60.03
2010	59.939
2011	59.866
2012	59.85
2013	59.959
2014	59.91
2015	59.813
2016	59.723
2017	59.709
2018	59.696
2019	59.682
2020	59.669
2021	59.655
2022	59.642
2023	59.628
2024	59.615
2025	59.601
2026	59.588
2027	59.574
2028	59.561
2029	59.547
2030	59.534