Year	Percent
1991	61.035
1992	56.872
1993	59.568
1994	58.636
1995	55.131
1996	55.101
1997	55.399
1998	57.204
1999	56.913
2000	58.405
2001	61.06
2002	62.511
2003	60.674
2004	70.264
2005	67.286
2006	64.216
2007	62.675
2008	63.038
2009	63.048
2010	57.525
2011	56.2
2012	52.463
2013	50.914
2014	50.43
2015	50.838
2016	48.436
2017	48.436
2018	48.402
2019	48.35
2020	48.296
2021	48.235
2022	48.178