Year	Percent
1991	8.411
1992	8.774
1993	9.007
1994	7.932
1995	7.57
1996	7.282
1997	6.945
1998	6.635
1999	6.413
2000	6.321
2001	6.03
2002	6.008
2003	5.561
2004	5.316
2005	4.859
2006	4.505
2007	4.375
2008	3.826
2009	3.79
2010	3.976
2011	3.829
2012	3.904
2013	3.769
2014	3.599
2015	3.927
2016	3.831
2017	3.801
2018	3.708
2019	3.641
2020	3.587
2021	3.534
2022	3.478