Year	Percent
1991	87.644
1992	88.124
1993	88.342
1994	88.309
1995	87.826
1996	86.414
1997	84.919
1998	82.183
1999	84.639
2000	84.658
2001	82.647
2002	82.925
2003	81.984
2004	78.844
2005	76.857
2006	75.872
2007	75.06
2008	74.039
2009	73.714
2010	72.742
2011	71.667
2012	70.865
2013	70.557
2014	69.392
2015	65.749
2016	64.213
2017	64.191
2018	64.098
2019	64.008
2020	63.924
2021	63.841
2022	63.761