Year	Percent
1991	34.188
1992	30.474
1993	26.298
1994	24.657
1995	23.853
1996	23.142
1997	22.271
1998	21.871
1999	22.794
2000	24.632
2001	26.514
2002	27.089
2003	27.139
2004	27.157
2005	26.682
2006	29.396
2007	31.873
2008	33.204
2009	32.857
2010	32.666
2011	30.019
2012	27.648
2013	28.792
2014	24.863
2015	25.934
2016	27.251
2017	26.435
2018	27.146
2019	27.704
2020	28.298
2021	28.88
2022	29.456