Year	Percent
1990	82.586
1991	82.552
1992	82.481
1993	82.332
1994	82.316
1995	82.261
1996	82.2
1997	82.169
1998	82.078
1999	82.02
2000	81.96
2001	81.949
2002	81.945
2003	81.971
2004	81.998
2005	82.037
2006	82.138
2007	81.362
2008	80.521
2009	79.607
2010	78.613
2011	77.541
2012	77.616
2013	77.673
2014	77.714
2015	77.728
2016	77.726
2017	77.482
2018	77.227
2019	76.965
2020	76.702
2021	76.441
2022	76.177
2023	75.917
2024	75.663
2025	75.419
2026	75.186
2027	74.963
2028	74.747
2029	74.535
2030	74.326