Year	Percent
1991	4.171
1992	3.818
1993	3.609
1994	3.385
1995	3.271
1996	3.185
1997	3.234
1998	3.116
1999	3.259
2000	3.045
2001	3.049
2002	2.906
2003	2.908
2004	2.887
2005	2.894
2006	2.813
2007	2.791
2008	2.168
2009	2.05
2010	2.029
2011	2.042
2012	1.955
2013	1.824
2014	1.792
2015	1.775
2016	1.671
2017	1.645
2018	1.616
2019	1.596
2020	1.578
2021	1.562
2022	1.548