Year	Percent
1991	6.565
1992	6.265
1993	5.964
1994	5.988
1995	5.302
1996	5.704
1997	5.32
1998	4.62
1999	4.382
2000	3.905
2001	3.781
2002	3.732
2003	3.429
2004	3.01
2005	2.917
2006	2.801
2007	2.586
2008	2.689
2009	2.846
2010	2.773
2011	2.406
2012	2.318
2013	2.259
2014	2.321
2015	2.199
2016	2.089
2017	2.09
2018	2.028
2019	1.969
2020	1.917
2021	1.873
2022	1.835