Year	Percent
1990	77.939
1991	78.146
1992	78.003
1993	77.863
1994	77.729
1995	77.603
1996	77.467
1997	77.335
1998	77.21
1999	77.096
2000	76.995
2001	76.942
2002	76.895
2003	76.85
2004	76.805
2005	76.757
2006	76.742
2007	76.718
2008	76.693
2009	76.671
2010	76.657
2011	76.657
2012	76.658
2013	76.43
2014	76.129
2015	75.779
2016	75.474
2017	75.507
2018	75.538
2019	75.572
2020	75.613
2021	75.659
2022	75.708
2023	75.762
2024	75.82
2025	75.885
2026	75.957
2027	76.033
2028	76.111
2029	76.189
2030	76.268