Year	Percent
1991	90.365
1992	90.042
1993	89.632
1994	89.28
1995	88.78
1996	88.198
1997	87.516
1998	86.421
1999	85.354
2000	80.995
2001	72.587
2002	81.344
2003	82.639
2004	83.622
2005	84.4
2006	84.803
2007	85.182
2008	84.871
2009	85.14
2010	85.233
2011	85.382
2012	84.805
2013	84.23
2014	83.569
2015	83.32
2016	83.349
2017	82.834
2018	82.542
2019	82.004
2020	81.803
2021	81.627
2022	81.449