Year	Percent
1991	85.01
1992	82.682
1993	80.474
1994	79.769
1995	79.116
1996	78.965
1997	79.454
1998	81.291
1999	82.749
2000	81.397
2001	82.118
2002	82.834
2003	82.994
2004	82.652
2005	89.104
2006	88.76
2007	89.343
2008	88.262
2009	89.314
2010	88.607
2011	88.117
2012	88.699
2013	88.723
2014	88.066
2015	86.14
2016	85.881
2017	85.871
2018	85.854
2019	85.82
2020	85.785
2021	85.751
2022	85.717