Year	Percent
1991	4.551
1992	4.539
1993	4.963
1994	4.993
1995	4.625
1996	4.273
1997	4.153
1998	3.652
1999	3.645
2000	3.407
2001	3.418
2002	3.191
2003	3.191
2004	3.242
2005	2.994
2006	3.346
2007	3.416
2008	3.354
2009	3.265
2010	3.118
2011	2.968
2012	3.026
2013	2.991
2014	2.942
2015	2.964
2016	2.695
2017	2.669
2018	2.626
2019	2.603
2020	2.582
2021	2.561
2022	2.54