Year	Percent
1991	59.157
1992	57.205
1993	53.539
1994	52.137
1995	52.649
1996	52.936
1997	54.004
1998	55.868
1999	58.034
2000	59.47
2001	60.622
2002	60.856
2003	61.307
2004	61.569
2005	63.139
2006	63.865
2007	63.85
2008	61.468
2009	55.668
2010	54.133
2011	52.641
2012	49.89
2013	48.732
2014	49.634
2015	51.258
2016	52.589
2017	53.793
2018	54.903
2019	55.092
2020	55.031
2021	54.775
2022	54.428