Year	Percent
1991	8.801
1992	8.552
1993	7.196
1994	6.83
1995	6.405
1996	5.612
1997	5.225
1998	5.067
1999	4.515
2000	4.352
2001	4.367
2002	3.932
2003	3.693
2004	3.16
2005	3.263
2006	3.322
2007	3.055
2008	2.829
2009	2.661
2010	2.714
2011	2.634
2012	2.574
2013	2.428
2014	2.403
2015	2.432
2016	2.511
2017	2.529
2018	2.48
2019	2.435
2020	2.391
2021	2.352
2022	2.317