Year	Percent
1990	81.566
1991	81.645
1992	81.621
1993	81.675
1994	81.446
1995	81.162
1996	81.119
1997	81.056
1998	80.959
1999	80.853
2000	80.727
2001	80.763
2002	80.835
2003	80.775
2004	80.667
2005	80.504
2006	80.508
2007	80.444
2008	80.413
2009	80.462
2010	80.474
2011	80.58
2012	80.604
2013	80.55
2014	80.456
2015	80.316
2016	80.205
2017	80.123
2018	80.03
2019	79.932
2020	79.834
2021	79.737
2022	79.641
2023	79.554
2024	79.486
2025	79.443
2026	79.422
2027	79.421
2028	79.437
2029	79.465
2030	79.503