Year	Percent
1990	4.35
1991	4.51
1992	3.89
1993	3.99
1994	3.63
1995	3.53
1996	3.66
1997	3.6
1998	3.21
1999	3.36
2000	3.14
2001	3.24
2002	3.32
2003	3.34
2004	3.44
2005	3.14
2006	3.28
2007	3.28
2008	3.39
2009	3.18
2010	3.16
2011	3.19
2012	3.42
2013	3.5
2014	3.68
2015	3.83
2016	3.98
2017	4.42
2018	4.78
2019	5.06