Year	Percent
1990	83.77
1991	83.573
1992	82.959
1993	82.682
1994	82.094
1995	82.051
1996	81.873
1997	81.597
1998	81.551
1999	81.3
2000	80.961
2001	82.54
2002	80.12
2003	80.512
2004	79.649
2005	78.308
2006	78.472
2007	78.151
2008	77.392
2009	77.111
2010	77.913
2011	78.675
2012	78.345
2013	79.386
2014	79.958
2015	80.788
2016	81.82
2017	81.965
2018	82.077
2019	82.173
2020	82.264
2021	82.327
2022	82.357
2023	82.366
2024	82.371
2025	82.383
2026	82.391
2027	82.402
2028	82.403
2029	82.363
2030	82.27