Year	Percent
1991	5.775
1992	5.734
1993	5.766
1994	5.67
1995	5.472
1996	5.301
1997	5.116
1998	5.047
1999	4.758
2000	4.478
2001	3.915
2002	3.817
2003	3.849
2004	3.657
2005	3.734
2006	3.628
2007	3.416
2008	3.313
2009	3.307
2010	3.209
2011	3.11
2012	3.025
2013	2.94
2014	2.837
2015	2.768
2016	2.686
2017	2.698
2018	2.673
2019	2.644
2020	2.623
2021	2.603
2022	2.584