Year	Percent
1990	77.568
1991	77.345
1992	77.093
1993	76.971
1994	76.861
1995	76.738
1996	76.921
1997	76.99
1998	77.553
1999	78.106
2000	78.65
2001	79.183
2002	79.706
2003	80.22
2004	79.132
2005	78.001
2006	76.827
2007	75.609
2008	74.349
2009	73.047
2010	71.704
2011	70.321
2012	68.9
2013	68.891
2014	68.871
2015	68.833
2016	68.781
2017	68.54
2018	68.299
2019	68.058
2020	67.817
2021	67.576
2022	67.334
2023	67.093
2024	66.852
2025	66.611
2026	66.37
2027	66.129
2028	65.888
2029	65.646
2030	65.405