Year	Percent
1991	4.536
1992	4.734
1993	4.469
1994	4.489
1995	4.578
1996	4.764
1997	4.977
1998	3.981
1999	4.155
2000	4.726
2001	4.97
2002	4.66
2003	4.643
2004	4.827
2005	4.839
2006	5.017
2007	5.105
2008	5.007
2009	5.18
2010	5.242
2011	5.478
2012	5.228
2013	5.471
2014	5.642
2015	5.638
2016	5.792
2017	5.91
2018	6.058
2019	6.179
2020	6.305
2021	6.427
2022	6.547