Year	Percent
1991	73.057
1992	74.178
1993	74.785
1994	73.684
1995	73.554
1996	71.997
1997	71.92
1998	71.648
1999	68.712
2000	67.764
2001	67.715
2002	67.165
2003	67.157
2004	67.655
2005	67.879
2006	68.503
2007	69.528
2008	69.246
2009	66.607
2010	69.388
2011	70.711
2012	70.853
2013	70.704
2014	69.957
2015	70.298
2016	69.598
2017	69.504
2018	69.576
2019	69.587
2020	69.586
2021	69.549
2022	69.502