Year	Percent
1991	69.401
1992	69.328
1993	67.492
1994	66.154
1995	66.58
1996	65.509
1997	64.475
1998	63.768
1999	61.956
2000	60.915
2001	60.029
2002	58.955
2003	58.078
2004	57.273
2005	56.804
2006	56.364
2007	56.134
2008	55.844
2009	55.686
2010	59.399
2011	58.609
2012	58.886
2013	60.409
2014	59.647
2015	57.979
2016	57.514
2017	57.863
2018	58.092
2019	58.229
2020	58.271
2021	58.202
2022	58.06