Year	Percent
1991	67.282
1992	67.002
1993	66.085
1994	65.572
1995	65.335
1996	64.59
1997	63.912
1998	62.915
1999	62.078
2000	61.369
2001	61.176
2002	60.816
2003	60.735
2004	61.066
2005	60.557
2006	61.471
2007	59.671
2008	57.91
2009	54.489
2010	55.712
2011	54.853
2012	54.062
2013	53.059
2014	54.658
2015	54.782
2016	54.113
2017	53.691
2018	53.222
2019	52.765
2020	52.36
2021	52.042
2022	51.779