Year	Percent
1990	7.7
1991	6.98
1992	7.48
1993	6.91
1994	7.41
1995	7.25
1996	7.48
1997	6.66
1998	6.19
1999	5.64
2000	5.38
2001	5.05
2002	4.71
2003	4.87
2004	4.12
2005	4.18
2006	4.34
2007	4.33
2008	4.28
2009	4.21
2010	4.01
2011	3.6
2012	2.82
2013	2.69
2014	2.84
2015	3.09
2016	3.19
2017	3.46
2018	3.73
2019	4.1