Year	Percent
1990	87.211
1991	86.086
1992	85.433
1993	85.984
1994	85.72
1995	86.676
1996	84.442
1997	85.529
1998	86.386
1999	85.134
2000	84.645
2001	85.403
2002	84.75
2003	85.058
2004	84.157
2005	84.774
2006	84.492
2007	85.122
2008	84.131
2009	83.122
2010	82.228
2011	83.119
2012	82.507
2013	82.361
2014	82.604
2015	81.616
2016	80.443
2017	80.591
2018	80.736
2019	80.857
2020	80.942
2021	80.994
2022	81.007
2023	80.997
2024	80.987
2025	80.993
2026	81.013
2027	81.046
2028	81.088
2029	81.135
2030	81.183