Year	Percent
1991	72.58
1992	73.392
1993	72.307
1994	72.548
1995	72.213
1996	71.885
1997	71.653
1998	71.012
1999	70.733
2000	70.084
2001	69.19
2002	69.02
2003	68.732
2004	68.111
2005	68.282
2006	68.638
2007	69
2008	68.797
2009	68.692
2010	68.245
2011	68.055
2012	67.604
2013	66.941
2014	66.194
2015	65.652
2016	65.337
2017	65.292
2018	64.894
2019	64.41
2020	63.935
2021	63.423
2022	62.908