Year	Percent
1990	74.085
1991	73.64
1992	72.928
1993	71.928
1994	71.71
1995	72.17
1996	71.841
1997	72.351
1998	72.85
1999	72.963
2000	73.387
2001	73.638
2002	73.899
2003	74.012
2004	74.086
2005	73.923
2006	73.994
2007	73.751
2008	73.53
2009	73.32
2010	72.991
2011	72.43
2012	72.012
2013	71.755
2014	71.29
2015	70.955
2016	70.92
2017	70.829
2018	70.75
2019	70.681
2020	70.62
2021	70.554
2022	70.499
2023	70.452
2024	70.414
2025	70.384
2026	70.347
2027	70.318
2028	70.294
2029	70.271
2030	70.245