Year	Percent
1991	59.58
1992	58.778
1993	58.251
1994	56.81
1995	55.145
1996	54.262
1997	57.621
1998	56.643
1999	56.255
2000	55.992
2001	53.607
2002	50.614
2003	48.898
2004	48.396
2005	49.294
2006	48.501
2007	37.953
2008	30.594
2009	32.804
2010	34.199
2011	37.518
2012	39.901
2013	39.63
2014	37.791
2015	36.68
2016	36.283
2017	35.589
2018	36.141
2019	36.002
2020	36.158
2021	36.301
2022	36.235