Year	Percent
1991	4.285
1992	4.388
1993	3.801
1994	3.735
1995	3.896
1996	3.988
1997	3.805
1998	3.817
1999	3.634
2000	3.586
2001	3.735
2002	3.795
2003	3.693
2004	4.288
2005	4.434
2006	4.658
2007	4.609
2008	4.223
2009	4.03
2010	3.649
2011	4.288
2012	4.392
2013	4.151
2014	4.15
2015	4.078
2016	4.031
2017	4.106
2018	4.111
2019	4.163
2020	4.152
2021	4.167
2022	4.182