Year	Percent
1990	82.908
1991	81.739
1992	80.81
1993	79.805
1994	78.704
1995	77.494
1996	76.138
1997	75.846
1998	75.61
1999	75.475
2000	75.46
2001	75.579
2002	75.762
2003	76.015
2004	76.352
2005	76.783
2006	75.872
2007	75.044
2008	73.182
2009	73.608
2010	73.044
2011	73.028
2012	73.012
2013	72.973
2014	72.891
2015	73.877
2016	75.205
2017	75.22
2018	75.147
2019	74.979
2020	74.713
2021	74.367
2022	73.927
2023	73.41
2024	72.846
2025	72.254
2026	71.65
2027	71.022
2028	70.388
2029	69.772
2030	69.191