Year	Percent
1988	4.69
1989	5.64
1990	5.41
1991	5.65
1992	5.8
1993	6
1994	6.18
1995	5.16
1996	4.57
1997	4.64
1998	4.93
1999	5.85
2000	4.91
2001	6.7
2002	8.66
2003	8.69
2004	9.04
2005	9
2006	7.4
2007	7.44
2008	8.27
2009	11.05
2010	9.37
2011	7.68
2012	7.18
2013	7.61
2014	8.73
2015	9.01
2016	9.69
2017	9.47
2018	9.65
2019	12.21
2020	11.77