Year	Percent
1991	87.133
1992	88.01
1993	87.614
1994	85.619
1995	83.535
1996	77.242
1997	82.516
1998	77.366
1999	79.153
2000	78.891
2001	73.586
2002	73.334
2003	70.552
2004	66.772
2005	65.007
2006	64.396
2007	62.623
2008	60.082
2009	59.792
2010	63.28
2011	62.776
2012	61.77
2013	62.938
2014	63.9
2015	66.009
2016	67.889
2017	68.847
2018	69.734
2019	70.071
2020	70.691
2021	70.741
2022	70.806