Year	Percent
1990	8.18
1991	9.21
1992	8.81
1993	8.15
1994	8.52
1995	7.87
1996	7.28
1997	6.72
1998	6.21
1999	5.73
2000	5.29
2001	4.89
2002	5
2003	4.83
2004	4.65
2005	4.84
2006	5.05
2007	5.58
2008	6.3
2009	6.6
2010	6.45
2011	6.15
2012	6.46
2013	6.6
2014	6.5
2015	6.47
2016	6.55
2017	6.72
2018	6.77
2019	6.86