Year	Percent
1991	8.485
1992	8.251
1993	8.112
1994	7.883
1995	7.679
1996	7.414
1997	6.981
1998	6.855
1999	6.427
2000	6.041
2001	6.043
2002	5.994
2003	5.857
2004	5.733
2005	5.565
2006	5.39
2007	5.141
2008	5.165
2009	5.428
2010	5.352
2011	5.072
2012	4.936
2013	4.866
2014	4.893
2015	4.74
2016	4.711
2017	4.771
2018	4.634
2019	4.51
2020	4.406
2021	4.307
2022	4.215