Year	Percent
1991	88.694
1992	88.467
1993	88.406
1994	88.202
1995	88.001
1996	87.91
1997	87.744
1998	87.608
1999	87.576
2000	87.42
2001	87.237
2002	92.219
2003	92.259
2004	92.264
2005	92.129
2006	92.021
2007	91.936
2008	91.784
2009	91.306
2010	91.086
2011	90.893
2012	90.781
2013	90.502
2014	90.213
2015	90.043
2016	89.958
2017	89.934
2018	89.905
2019	89.881
2020	89.858
2021	89.836
2022	89.816