Year	Percent
1989	4.24
1990	3.6
1991	4.05
1992	3.45
1993	4.11
1994	4.62
1995	6.83
1996	6.5
1997	5.67
1999	16.16
2000	14.7
2001	20
2002	18.19
2003	14.97
2004	14.97
2005	16.14
2006	16.78
2007	15
2008	9.93
2009	8.34
2011	8.51
2012	7.61
2013	7.34
2014	8.53
2015	6.89
2016	7.7
2017	7.06