Year	Percent
1991	74.691
1992	75.092
1993	74.784
1994	74.948
1995	74.853
1996	74.838
1997	74.719
1998	74.412
1999	74.138
2000	73.804
2001	73.36
2002	72.964
2003	72.689
2004	72.318
2005	71.32
2006	71.329
2007	70.341
2008	70.178
2009	69.616
2010	69.055
2011	68.28
2012	67.734
2013	66.91
2014	65.394
2015	64.888
2016	64.292
2017	63.833
2018	63.129
2019	62.451
2020	61.716
2021	61.005
2022	60.329