Year	Percent
1991	66.766
1992	66.69
1993	66.554
1994	66.473
1995	66.391
1996	65.942
1997	65.553
1998	65.27
1999	65.076
2000	65.241
2001	65.395
2002	65.594
2003	65.889
2004	66.244
2005	66.701
2006	67.028
2007	67.443
2008	67.934
2009	68.427
2010	68.737
2011	69.415
2012	69.796
2013	70.181
2014	70.446
2015	70.634
2016	70.602
2017	70.349
2018	70.031
2019	69.67
2020	69.28
2021	68.714
2022	68.131